Murderers will often dispose of bodies in areas they are familiar with because they can assess the risks of being caught in the act. Two skulls (one belonging to Donna Lass) and a jawbone were found in the general area surrounding Lake Spaulding and possibly Fuller Lake (3.5 miles north of Emigrant Gap and Interstate 80, where Drum Canal crosses State Route 20), and matching the location of the skull described in the death certificate of Donna Lass. The Lake Spaulding Dam and Fuller Lake are both part of the Drum-Spaulding hydroelectric system, operated by PG&E (Pacific Gas & Electric Company). In fact, two workers from PG&E discovered the skull of Donna Lass in a drainage ditch according to The Doe Network and death certificate. The question being: was the murderer of Donna Lass familiar with these PG&E locations, such that he used them as relatively safe deposition sites? Could we have one killer who used this location to conceal a minimum of two bodies?

​This may appear like grasping at straws, until you consider that a skull fragment of Joanne Dolly Burmer (25) was found by a man cutting firewood on Chalk Bluff Road on May 30th 1993, and not identified until a DNA breakthrough in 2019, when matched through her son, who was 3 years old when she went missing. Joanne Burmer was belatedly reported missing on March 8th 1973, having been dropped off by friends nine days earlier at the junction of Highway 20 and Excelsior Point Road on February 27th 1973. This location is just 3 miles from Emigrant Gap, and 4.5 miles from Lake Spaulding.  

​On February 27th 1973, after she was dropped off by friends, including Ron Inman, she had planned to snowshoe to see her on-off boyfriend Robert Brownlee, who lived in a cabin about 3 miles away. She was never seen again, with detectives suspecting foul play. Philip Desmet, son of Joanne Burmer (adopted after her disappearance) thought that Robert Brownlee was a womaniser: “My mom was a hippie” he said, adding that she had been living in a Quonset hut just outside Colfax, bouncing between there and Reno, and had worked for a while at a local bar. At some point, Joanne married a man named Robert Burmer, but then became involved in a tempestuous relationship with Brownlee. "He was a womanizer, apparently”. Desmet said. “My understanding is, she was the other woman, and she was going up there to deliver an ultimatum (to him)".

Ron Inman and Burmer’s mother, Ruth Schroll, told investigators that Robert Brownlee and Joanne Burmer had frequent fights, sometimes violent. He was obviously a prime suspect in her disappearance and possible murder, but as of writing, this case is still unresolved. Robert Brownlee worked for PG&E to maintain the quality of their canals. The skull of Donna Lass, who went missing on September 6th 1970, was found in a drainage ditch by two PG&E workers in 1986 (if The Doe Network and death certificate are correct). See here. Pacific Gas and Electric Company (PG&E) operates an extensive hydroelectric system in California that includes approximately 172 miles of canals. Did somebody like Robert Brownlee ever visit the Sahara Tahoe Hotel & Casino in 1970 - a possible womaniser with a short temper according to accounts, who must have been knowledgeable of the locations around Lake Spaulding and the Drum Canal crossing due to his working experience with PG&E.

​PG&E honored 4,183 employees with long service awards in 1975, with Robert E. Broenlee of Emigrant Gap receiving a 15 year award according to the newspaper cutting below. However, newspapers reported he received a 15 year award in 1980 as well, followed by a 20 year award in 1985. Therefore, it's evident that the 1975 award should have been for 10 years service. This means he was first employed by PG&E in 1965, so would probably have been at least in his early 20s in 1970 and around his mid 20s in 1973. Indications through ancestry searches suggests somebody much older, who may have been 47 in 1973.  He was still employed at PG&E in 1985, so one would presume he still lived in the Emigrant Gap area at the time the 1986 remains were found. Thanks to Jibberjabber for this extra information and newspaper cutting below.

Once again we have the death certificate of Donna Lass doing the rounds, stating that her skull was found on July 31st 1986 by State Route 20, 3.5 miles north of Interstate 80, near the Drum Canal crossing by Emigrant Gap (which I have examined below on Google Maps). It has been argued that an upper jawbone (maxilla) was found near Chubb Lake on December 31st 1985 by a fisherman traveling towards Yuba Gap and Lake Valley Reservoir, followed by a skull discovered in the region of Emigrant Gap seven months later, which was identified through DNA as belonging to Donna Lass, with the two finds not necessarily related. On The Doe Network it states that the date of discovery of the skull in a drainage ditch was August 5th 1986 rather than July 31st 1986, but who's quibbling over a few days. The Agency Case Number: 13226-86 on this page matches the case number on the certificate of death, so it must be case closed - the skull of Donna Lass was found in a drainage ditch near the Drum Canal crossing by Emigrant Gap in July or August of 1986. The eastern edge of Drum Canal sits approximately 3/4 mile west of Lake Spaulding Campground (see map below). 

​There were newspaper reports in 1986 of a skull being found in a drainage ditch:between July 31st and August 5th 1986, like so: "Aug. 4, 1986 – PG&E workers found a human skull in a drainage ditch near Highway 20 and I-80. The skull is believed to be that of a Caucasian female in her mid-teens to early 20s". Drum Canal joins PG&E Road near the Blue Canyon (Pacific Gas & Electric Company). However, this skull wasn't found by the sheriff's search party headed by Deputy Lowell Carlton, who used scent dogs to look for further remains in the Yuba Gap area after the jawbone was discovered on December 31st 1985. It was found by PG&E workers (two men) seven months later, slightly west of Lake Spaulding near Emigrant Gap. After the jawbone was found near Chubb Lake (Yuba Gap) on December 31st 1985, a belated search of the "immediate area" (hampered by bad weather) was undertaken by Deputy Lowell Carlton, who found a skull on January 19th 1986 in close proximity to the jawbone. Sheriff Donald Nunez said in January 1986 after the discovery of the skull, that a jawbone was "also found along the road TO the Lake Valley Reservoir". Both skull and jawbone were found alongside Lake Valley Road, which is a county road running from Chubb Lake to Lake Valley Reservoir. 

Lake Spaulding Campground is located in the Sierra Nevada mountain range near Soda Springs, California. The lake is surrounded by giant granite boulders and thick pine forest. Lake Spaulding offers a range of water activities including all types of boating and there is a boat ramp which allows for easy access. Walk-in tent sites and a limited amount of overflow parking spots in the boat launch parking area are available. RV's and trailers longer than 30 feet are NOT recommended for sites in the campground loops. Drinking water, vault toilets and picnic areas are provided. Lake Spaulding Campground is included in the recreation area managed by Pacific Gas and Electric Co. in Northern California. Lake Spaulding Dam is a dam in Nevada County, California. Owned and operated by Pacific Gas & Electric for hydroelectric power generation, the 275-foot (84 m)-high dam was designed by John R. Freeman and completed in 1913. Fuller Lake is a 70-acre reservoir located in the Sierra Nevada mountains near Nevada City, California, that is owned and operated by the Pacific Gas and Electric Company (PG&E) as part of its Drum-Spaulding hydroelectric system. The lake is located 3.5 miles north of Emigrant Gap and Interstate 80 (where Drum Canal crosses State Route 20), and can be accessed by Bowman Lake Road. Fuller Lake is a Day Use area just like the murder site at Lake Berryessa.​​

The NamUs page of unidentified persons in 2018 correctly identified the jawbone (maxilla) found by fisherman Melvin Bennett on December 31st 1985, but failed to mention anything about a skull being found in the "immediate area", by stating "head not recovered". One could be forgiven in believing the jawbone and skull, both found alongside Lake Valley Road, were very likely from the same individual, unless we make the argument that two separate victims were the product of one killer and one dumping ground. On The Doe Network, the skull found in Placer County in late July or early August 1986 in a drainage ditch by two PG&E workers, has been given an estimated time of death of 2 to 3 years (and was partial skeletal), meaning 1983 or 1984. The website states "The decedent's skull was discovered in a drainage ditch near Interstate 80 and State Highway 20". Realistically, Donna Lass was murdered in September 1970, at least thirteen years earlier than this estimate. If this was the case, she would have been fully skeletonized like the skull found at Yuba Gap. 

When the news broke that Donna Lass had been identified in 2023 through DNA from the skull, many newspapers reported the following: [1] MSN: "A deputy sheriff found the remains near California's Sierra Nevada mountains, along Highway 20 and Interstate 80- 45 miles northwest of South Lake Tahoe in 1986. The skull was held on to until there were more forensic technology advancements". [2] SACRAMENTO BEE "In 1986 the Placer County Sheriff's office found a skull near Highway 20, not far from Interstate 80, in the Camp Spaulding area". [3] NBC NEWS: "A sheriff’s deputy found the skull in 1986 along Highway 20 and Interstate 80, 45 miles northwest of South Lake Tahoe, the Placer County Sheriff's Office said. It was preserved at the coroner's office as an unidentified person". Yuba Gap is exactly 45 miles from the south side of the lake. [4] FOX KTVU: "Placer County Sheriff's deputies later found an unidentified skull in 1986 and held on to it until there were more advancements in forensic technology, KCRA3 reported". These articles are but a small sample (I could have added many more) The Donna Ann Lass "Find a Grave" page states "In 1986, a sheriff's deputy found the skull of an unidentified person along a highway in the Sierra Nevada mountains of California. In December of 2023, a match was discovered between DNA taken from the skull and that taken from Donna's sister The result was that the skull was identified as being that of Donna Lass, finally providing the evidence to prove that Donna was actually deceased". That "sheriff's deputy" was Lowell Carlton, who found a skull on January 19th 1986 at Yuba Gap in close proximity to the jawbone, not the PG&E workers who found a different skull slightly west of Lake Spaulding in July or August.

​I am assuming these newspaper outlets were given this information by Placer County law enforcement, who linked the skull found by Deputy Sheriff Lowell Carlton and his scent dogs, to the DNA identifying Donna Lass in 2023. Otherwise they should have mentioned the PG&E workers, which they didn't. I believe the death certificate and The Doe Network case numbers have been incorrectly linked together, but without any further information about the DNA from the jawbone, I will let you decide whether the skull of Donna Lass was found alongside Lake Valley Road in Yuba Gap, or somewhere north of ​the Drum Canal crossing by Emigrant Gap, west of Lake Spaulding. I am open to being wrong, as pointed out by Travis Miller, who successfully acquired the FBI files of Donna Lass through some excellent research. Either way, we have two skulls by Interstate 80 in close proximity to one another.
​
The murderer of Donna Lass, if he had after hours drinks with her at the Sahara Tahoe Hotel or another bar on September 6th 1970, had every reason to make a phone call on September 7th 1970 claiming she had been called out of town for a family illness - and to conceal the body many miles from her residence (70 miles). An immediate investigation into her absence from work (or immediate discovery of her body) would have meant police interviewing anybody in the company of Donna Lass after she was last seen at around 2:00 am at the casino. This would have been their prime focus and required interviewing any potential eyewitnesses to her movements that morning, whose memories and recollections would have been much more reliable after only a few hours and days, rather than weeks. The longer the perpetrator could delay the investigation into her disappearance (and murder), the better it was for him. The killer, if seen with Donna in the hours after her shift ended, needed to confuse the time of her death and make the timeline widen, had her body been found in the near future. This tactic worked, because the police investigation into her disappeaance was badly delayed and hampered. A random killer, with no backstory regarding Donna, who just entered her apartment on September 6th 1970 and was not present in her company in the previous few hours, had absolutely no reason to phone the Sahara Tahoe Hotel and concoct a fake story about her absence from work. This phone call had purpose. To widen the parameters of any future investigation, and to reduce the focus on the immediate few hours after 2:00 am on September 6th 1970. It appears that her murderer knew the importance of those few hours. 

A KILLER FROM THE CASINO [PART ONE]     A KILLER FROM THE CASINO [PART TWO]

​VISIT LAWRENCE KANE AT WORDPRESS FOR MORE INFORMATION 

In the last article I examined the likelihood of a killer who either worked at the Sahara Tahoe Hotel & Casino, or somebody who frequented the establishment regularly and knew well the details of Donna Lass, who worked at the casino as a nurse, The FBI files suggested that Donna Lass' vehicle had remained in the parking space outside her apartment when she left for work on September 5th 1970. This would make sense had she planned to go out for some alcoholic beverages after her shift ended at 2:00 am on September 6th 1970. By all accounts Donna Lass was a responsible young woman, who probably chose to walk the 3/4 mile (15 minute) journey to work that afternoon, to begin her shift at the Sahara Tahoe Hotel at 6:00 pm, rather than drink and drive. This has some validity, because just before the end of her shift she changed into a fashionable navy blue slack suit with matching shoes and purse/handbag. Investigators discovered that Donna occasionally went for drinks after work.

It was outlined in the previous article that many things about this case point to a killer who knew intimate details about the life of Donna Lass. The sinister phone call on September 7th 1970 stated that Donna Lass had been called out of town because of a family illness, that would have failed to have the desired effect of "buying time" had her family lived in South Lake Tahoe rather than Sioux Falls, South Dakota. The killer must have been aware of this personal information. The phone call wasn't made prior to 6:00 pm on September 6th 1970 excusing her absence from work, suggesting that the perpetrator knew she wasn't due in work that day. The phone caller (according to the private investigator's report) used the name of her new landlord, by claiming he was "Mr. Davis" (Nick Davis) when reporting Donna's absence due to a family illness. Nick Davis vehemently denied he was the one who made the call to Gordon Petrovich, a security guard at the Sahara Tahoe Hotel.

It should be pretty obvious the caller wasn't Nick Davis, because if he had murdered Donna Lass on the morning of September 6th 1970, he most certainly wouldn't have given his name over the phone and implicated himself in her disappearance (and murder) by giving a fake story of a family illness, which when uncovered during the resulting investigation would inevitably have drawn interest from law enforcement. The person who gave this fake story, not only knew her family lived "out of town", but knew to use the name of "Mr. Davis" when ringing the Sahara Tahoe Hotel on September 7th 1970, which would have added a level of credibility to her absence.

​This detail is absolutely crucial, because Donna Lass only signed her tenancy/rental agreement on September 5th 1970, before she left for work that day. That means that the killer very likely learned this information from Donna Lass between the time she signed the rental agreement and the time of her murder, sometime before the phone call on September 7th 1970. It is certainly plausible that Donna Lass could have shared the information of her new landlord and apartment in the few hours after her shift ended at 2:00 am, with whomever she went for a drink with (if this transpired). The sort of information she would obviously have been excited about, having now secured an apartment of her own. If the person she went for a drink with was a colleague, friend or acquaintance, it is not unreasonable to assume she told them she wasn't due in work later that day. Hence why the malicious phone caller rang the casino on September 7th 1970 rather than the day before, and gave the name of "Mr. Davis" to add validity to the story and deflect suspicion away from themselves. This is why we should focus on colleagues and friends Donna had previously drank with.

If Donna Lass was heading off for a drink with individuals such as the ones described in the private investigator's report above, then these are the sort of people who could conceivably have known enough about Donna's life to make that phone call. Of course, these particular men may have played no part in the disappearance and murder of Donna Lass, but Ramon Vascuas admitted he saw Donna several times on the Labor Day weekend and had previously drank with her, just not during the crucial time period of her disappearance because he was "very busy". The Lowe's, who Donna Lass had previously lived with for several months, claimed that Ramon Vacuas, a worker at the Sahara Tahoe Hotel, had once dated Donna Lass and attempted to kiss her, before being rebuffed.

A male by the name of Tony Chapman, who never "really" dated Donna, openly admitted to having after work drinks with her for several hours at a time. On one occasion up to 5:00 am in the morning. And another until 4:00 am, accompanied by his roommate Vern Lauflin, who both seemingly lived at 3608 Terry Lane in an apartment complex similar to Donna's (unless it was typed incorrectly in the report). The apartment at 3608 Terry Lane is 3/4 mile beyond the home of Donna Lass and sits close to Pioneer Trail Road.

​If Donna had drank with these gentlemen previously and was absent of her vehicle on those occasions, it is not unreasonable to conclude that she would likely have walked with both (or either) as they traveled home. After all, they shared a common route along Pioneer Trail Road. The alternative, is that she accepted a lift home from them (assuming they had a vehicle). If Donna Lass had left her vehicle at her apartment complex on September 5th 1970 and got changed into her civilian clothes on September 6th 1970 at 2:00 am, before meeting up with somebody for a drink, then it is not inconceivable she opted to walk, or accept a lift from such a person. Somebody who courteously escorted her directly to her front door - and possibly beyond. Her purse/handbag, with personal cosmetics, check book and money, apparently made it home that morning, but the clothes she was last seen wearing at the Sahara Tahoe Hotel on September 6th 1970 at 2:00 am, just disappeared into the night. 

PREVIOUS ARTICLE: A KILLER FROM THE CASINO? [PART ONE]     

I am sure Donna Lass (25) was as fashion conscious as any other young women in 1970, so it isn't that surprising that she was described as wearing a blue slack/pant suit, blue shoes and carrying a blue purse (handbag) on September 5th 1970 by somebody at the Sahara Tahoe Hotel & Casino. A color coordinated selection of fashion accessories worn by Donna Lass before her shift began at 6:00 pm. This civilian outfit was missing from her apartment when belatedly searched by investigators when concerns grew about her absence from work, but her purse was found at her home containing her check book, car keys, personal cosmetics and a wallet containing less than $25. This strongly suggests that she arrived back to her apartment in the early morning hours of September 6th 1970, had removed her purse/handbag from her shoulder, but had failed to remove her clothing to go to bed.

​It is highly unlikely somebody entered her apartment in the middle of the night and forced her to get dressed into the same clothing she had worn just a few hours earlier, before abducting and/or murdering her. It is also noteworthy that her purse was seemingly untouched, still containing a wallet with some money (less than $25), a check book and the keys to her 1968 Chevrolet Camaro. These items were seemingly not of interest to the perpetrator. 

The FBI files stated that Donna Lass wore contact lenses, that one would presume she wore to perform her duties as a nurse at the Sahara Tahoe Hotel & Casino. If these were missing from the apartment when searched by investigators, it should have become obvious that she had worn them during her shift, and had failed to remove them before going to sleep that morning (which most people do). This would mean that she arrived back at her apartment, separated herself from her purse/handbag, but had not yet removed her blue suit and contact lenses in preparation for bed (which obviously would both be missing).

​This may give us a narrow corridor of time for her murder and/or abduction, by a perpetrator who arrived home with her from the casino with malintent, or somebody in the vicinity of the Pioneer Trail residence who saw her arriving back on the morning of September 6th 1970, and seized the opportunity as she unlocked the front door of her apartment (or shortly afterwards). These two scenarios would explain why both her blue suit and contact lenses were missing from her 3893 Pioneer Trail Road home, but her purse/handbag and personal items were not. This would indicate that Donna Lass met her demise, whether by murder or abduction, shortly after arriving home. 

It was noted by investigators that Donna Lass had changed into civilian clothes just before the end of her shift, which she occasionally did when she went to one of the bars for a drink (see below). Why would she change into a fashionable, color coordinated set of clothing at around 1:50 am, if her only intention was to travel home and go to bed? This may have been one of those occasions when she met up with somebody for a drink, who either drove her home afterwards, or she invited them to her new apartment (in her vehicle). Somebody who knew her work schedule, knew she wasn't working the evening of September 6th 1970 and could phone the casino explaining her absence the following day, knew that Mr. Davis was the name of her new landlord when pretending to be him during the malicious phone call on September 7th 1970, and knew they had to confuse the exact time of Donna's murder by claiming she had been called out of town for a family illness. A family that the killer knew lived out of town (in Sioux Falls, South Dakota). A location he hoped would buy him time and delay any investigation, which it ultimately did. If the killer of Donna Lass thought there was any chance of him being recognised as being with Donna Lass on the morning of September 6th 1970 (possibly having a drink), then it would be greatly beneficial to him that she wasn't found murdered the same or following day. By delaying any investigation into her absence through a phone call and body disposal, it blurs the timeline and memories of any potential eyewitnesses, and the exact day and time of her murder (if she had been found a week or so later). It would have created reasonable doubt in the mind of investigators during any forthcoming interrogations and the ultimate pursuit of justice. If I had to roll the dice, I would expect the casino to hold the answer in the murder of Donna Lass.

FURTHER READING: A KILLER FROM THE CASINO? [PART TWO]

On October 14th/15th 1969 the "Zodiac Killer" made a phone call to Santa Rosa claiming he was going to place bombs on school buses, thereby proving this was from the real killer of five people. This call came before the contents of the October 13th 1969 letter threatening schoolchildren was released into the public domain. In fact, this was the first mention of bombs, nearly a month before the Zodiac Killer's "Bus Bomb" letter was mailed to the San Francisco Chronicle on November 9th 1969. However, this probably wasn't the only time the Zodiac Killer threatened to blow up school buses prior to the arrival of the "Bus Bomb" letter. The second set of phone calls threatening school buses likely began in the latter days of October or early November, and continued for several weeks, before culminating on November 24th 1969.

These threats were made to the Lake Tahoe region and Incline Village, the location featured in the Zodiac Killer's "Pines" card on March 22nd 1971. It must be noted that these threats began seven months before Donna Lass relocated from the Letterman General Hospital in the Presidio to South Lake Tahoe. The newspaper article below is from the Sacramento Bee on November 24th 1969, describing a series of malicious calls "received during the last few weeks". If we take a "few weeks" to mean 3 or 4 weeks, it would suggest that these calls began on November 3rd 1969 at the latest, and continued throughout the duration the Zodiac Killer was composing his "Bus Bomb" letter. In other words, if you believe the Lake Tahoe school bus threats were made by a hoaxer (and don't believe the Zodiac Killer made the Santa Rosa phone calls in October), you are left with an individual mimicking the Zodiac Killer's bomb threats before the Zodiac Killer even made any bomb threats on school buses himself.    

We likely now have two instances of bus bomb threats being made upon schoolchildren from somebody claiming to be the "Zodiac Killer", prior to the first mention of bombs in the verified "Bus Bomb" letter on November 9th 1969. But don't expect this to sway the majority of the Zodiac community into deviating from the well worn narrative they have become accustomed to over the years. They are fixated and unflinching in the belief we have only four Zodiac ciphers, two Zodiac phone calls, and about twenty Zodiac letters. No amount of evidence will ever change this.

The "Bus Bomb" letter and Lake Tahoe phone calls coincided with a two week threat towards school teacher Daniel Williams in Martinez (from October 22nd to November 5th 1969), in which he endured malicious phone calls from the "Zodiac Killer" and an attempted poisoning by arsenic. The phone caller stated he "had gone to a Martinez school in search of victims but left when he found police there", but they wouldn't catch him because, as he stated “I’m too smart for them". A few days later, the Zodiac Killer mailed the "Bus Bomb" letter bragging that "The police shall never catch me, because I have been too clever for them". He also supplied crosshairs with five X's on its circumference, which when tilted close to magnetic north, landed over every crime he was claiming thus far, apart from the X on the 9 o' clock position. When a line was drawn through this position, it traveled directly over the Salesian High School where Daniel Williams worked as a teacher. We now have three occurrences in early November 1969 - all related to the targetting of school buses and/or schoolchildren. It's amazing how many of these hoaxers knew what the Zodiac Killer was going to do before he did. Quite amazing.    

In the previous article I covered William Frederick Friedman and the "CSP 888" cipher machine, a highly secure, electromechanical rotor-based cipher machine used for top-level communications during World War II. Friedman was instrumental in leading the Army's cryptologic services during the 1920s and 1930s, which set the stage for the development of secure machines like the CSP 888. There is much reason to connect Edgar Allan Poe to the design of the Zodiac Killer's Z340 and Z13 through his cryptographic works, such as Poe's July 1841 essay "A Few Words on Secret Writing", which William Friedman mentioned in his 1937 bulletin entitled “Edgar Allen Poe, Cryptographer”.

​In Poe's essay, the alphabet was split A through M and N through Z, which was seemingly adopted by the Zodiac Killer on April 20th 1970, beginning and ending his ciphertext characters with the letters A and M, in an array of characters totalling thirteen (half an alphabet). To then find the three circled 8's present in the cipher and possibly mimicking the cipher machine "CSP 888", was extremely interesting (whether deliberate or accidental). Especially when you consider that William Friedman and Edgar Allan Poe are bound together by the words in “Edgar Allen Poe, Cryptographer” (1937), written by Friedman, whose career in the field of cryptology was originally inspired by Edgar Allan Poe. Was the Zodiac Killer influenced by the cryptographic work of William Friedman, who drew upon his knowledge of this individual when he was challenged by Donald C. B. Marsh of the American Cryptogram Association inviting the Zodiac Killer to mail a cipher which truly included his name?  A challenge published in the San Francisco Examiner on October 22nd 1969, just 17 days before the Zodiac Killer mailed his infamous 340 cipher on November 8th 1969, which may also have been influenced by the works of William Friedman.

The 340 cipher was finally cracked in December 2020 by David Oranchak, Sam Blake and Jarl Van Eycke, who discovered that the cipher was a combination of substitution and transposition (using frequency analysis). The Riverbank Publications is a series of pamphlets written by the people who worked for millionaire George Fabyan in the multi-discipline research facility he built in the early 20th century near Chicago. They were published by Fabyan, often without author credit. The publications on cryptanalysis, mostly written by William Friedman, with contributions from Elizebeth Smith Friedman and others, are considered seminal in the field. In particular, Publication 22 introduced the Index of Coincidence, a powerful statistical tool for cryptanalysis. 

​William Friedman's work on transposition ciphers at Riverbank Laboratories (circa 1916–1920) established foundational, mathematical techniques for solving complex reordering ciphers. Notably, Riverbank Publication No. 19, Formulae for the Solution of Geometrical Transposition Ciphers, provided analytical methods to solve transposition, which he compared to reassembling jigsaw puzzle pieces. It's quite ironical that the title of Friedman's work was called Riverbank Publication No. 19, Formulae for the Solution of Geometrical Transposition Ciphers, when a period 19 shift was required to break the Zodiac Killer's 340 transposition cipher. This was a fraction of the work issued by William Friedman. But was he the inspiration for the Zodiac Killer, who employed this type of cipher on November 8th 1969? 

​Unfortunately, there is one final intriguing aspect to this story - and sadly it's very final. Just six days before the 340 cipher was mailed on November 8th 1969, William Frederick Friedman died of a heart attack at the age of 78. He passed away on November 2nd 1969, about a week before the Zodiac Killer's transposition cipher arrived at the San Francisco Chronicle. He was buried with full military honors at Arlington Cemetery on November 5th 1969. 

THE 888 CIPHER MACHINE USED IN WORLD WAR II

The Zodiac Killer was riding high in October 1970, currently sitting on four unbroken ciphers he had mailed on November 8th 1969, December 7th 1969, April 20th 1970 and June 26th 1970. On October 6th 1970 the Zodiac Killer would mail the 13-Hole "Punch Card" with thirteen holes punched through the fabric of the card, while simultaneously declaring himself "crackproof". His use of the words "crack" or "cracked" were usually chosen when referring to his ciphers, so one could conclude that the thirteen punch holes in the card, having been mailed 5 1/2 months after his 13-Symbol cipher on April 20th 1970, which contained the words "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is....", could be related.

​Creating thirteen punch holes in the card (previously used in coding machines), in combination with the word "crackproof", may suggest a link between the two communications mailed on April 20th 1970 and October 6th 1970. Especially when you consider no cipher was included in the card mailed in October. It has previously been shown that the 13 punch holes were positioned in a 10:3 configuration, with the 3 punch holes placed directly below where they sat in the 13-Symbol cipher on April 20th 1970 (see below). If these two communications were linked together, we need to examine the Zodiac Killer's decision to use punch holes, his choice of the word "crackproof", and his selection of the three circled 8's in his 13-Symbol cipher, to see if we can connect all three to one encipherment technique or coding machine.  

The Zodiac Killer was "about 40" years of age in 1969 according to the three sets of eyewitnesses at Presidio Heights, so he would have been around 16 (or possibly slightly older) at the time World War II ended. If he had an interest in cryptography, he would almost certainly have known about Alan Turing, a British mathematician who led the crucial World War II effort at Bletchley Park, England to crack the German Enigma machine, an electromechanical rotor device used for secure military communications. This cipher machine is arguably the most famous cipher machine in the world, but it was far from unbreakable. 

It was clear to US cryptographers well before World War II that the single-stepping mechanical motion of rotor machines (e.g. the Hebern machine) could be exploited by attackers. In the case of the famous Enigma machine, these attacks were supposed to be upset by moving the rotors to random locations at the start of each new message. This, however, proved not to be secure enough, and German Enigma messages were frequently broken by cryptanalysis during World War II. William Friedman, director of the US Army's Signals Intelligence Service, devised a system to correct for this attack by truly randomizing the motion of the rotors. His modification consisted of a paper tape reader from a teletype machine attached to a small device with metal "feelers" positioned to pass electricity through the holes. When a letter was pressed on the keyboard the signal would be sent through the rotors as it was in the Enigma, producing an encrypted version. In addition, the current would also flow through the paper tape attachment, and any holes in the tape at its current location would cause the corresponding rotor to turn, and then advance the paper tape one position. In other words, the punch holes were a key ingredient to the encipherment process. link.

SIGABA (also known as the ECM Mark II) was primarily developed by a team of American cryptographers in the mid-1930s, with key contributions from William Friedman. The device was an electromechanical rotor-based cipher machine developed in the late 1930s in the United States as a joint effort of the US Army and US Navy  At the time it was considered a superior cipher machine, intended to keep high-level communications absolutely secure. It was used throughout WWII and was so reliable that it was used well into the 1950s, after which it was replaced by newer machines like AFSAM-7 (KL-7). As far as we know, SIGABA was never broken by Axis powers. In other words it was the primary encryption technique used in World War II by America - and to the best of our knowledge - remained "crackproof" throughout its service.

This gives us the "punch holes" in paper and the "crackproof" elements, but where do we find the "888" present in the 13-Symbol cipher, that was possibly highlighted in the 13-Hole "Punch Card"? The U.S. Army called the cipher machine SIGABA or Converter M-134. The U.S. Navy called the machine the CSP-888 (Cryptographic Security Publication) and CSP-889. The machine has three banks of 5 rotors each. The main bank (at the rear) holds 5 rotors with 26 contacts each. These are the main cipher rotors. They work in a similar way as the rotors of the con­temporary German Enigma machine.

The 13-Symbol cipher on April 20th 1970, many believe was a response to the challenge by Donald C. B. Marsh, who told the San Francisco Examiner on October 22nd 1969: "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allan Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name, in cipher code, would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code, however complicated, which will truly and honestly include his name". 

By invoking the name of Edgar Allan Poe, it was probably hoped that the Zodiac Killer would use one of the cryptographic techniques described (or used) by Poe in his famous works, such as "A Few Words on Secret Writing", which contained all the ingredients used in the decryption of the 340 cipher and the design of the 13-character code, including the scytale method of decryption, the splitting of the alphabet, A throgh M and N through Z, and the cipher wheel, which uncovers a potential message in the Z13 code. The SIGABA cipher machine has room for three rows (or banks), of five cipher wheels each.

​In total, we have 13 punch holes and 13 ciphertext characters, a famous "crackproof" cipher machine and the same declaration by the Zodiac Killer on October 6th 1970, the 10:3 configuration on the "Punch Card" possibly highlighting the position of "888" as the key in the April 20th 1970 letter, the CSP-888 cipher machine used by the U.S. Navy in World War II, the cipher wheel explained by Edgar Allan Poe in July 1841 in A Few Words on Secret Writing, prompted by cryptographer Donald C. B. Marsh in a newspaper article on October 22nd 1969, and the signature of "ME⊕" revealed in the Z13 by using three right shifts of 8, which was also present in the Exorcist letter on January 29th 1974. The other possibility, is we have nothing. 

`` Edgar Allan Poe (1809–1849) popularized cryptography in the 1840s through stories like "The Gold-Bug," prompting a young William Friedman (1891–1969) to pursue the field. While Friedman became a legendary U.S. Army codebreaker who valued Poe’s role as a catalyst, he famously critiqued Poe’s actual cryptanalytic skills as amateurish in his 1936 analysis, "Edgar Allan Poe, Cryptographer". Could we therefore have a crossover between the cipher machine CSP-888 and the essay of Edgar Allan Poe, A Few Words on Secret Writing, manifesting itself on April 20th 1970? A Few Words on Secret Writing is mentioned by William Friedman on page 146 of his analysis (see below).  

​​William F. Friedman on Edgar Allan Poe
THE FRIEDMAN LECTURES ON CRYPTOLOGY

FOLLOW UP ARTICLE: A FEW DAYS AFTER DEATH 

It was common for the Zodiac Killer to compose letters and cards inspired by newspaper articles he had recently read, so it wouldn't have been out of the ordinary for the murderer of five to have been a regular consumer of the San Francisco Chronicle, including the games and puzzles section. On November 8th 1969 the Zodiac Killer mailed his infamous 340 cipher, unsolved for 51 years, until it was cracked by David Oranchak, Sam Blake and Jarl Van Eycke in 2020 using a knight's move (period 19) decryption technique. Could the Zodiac Killer have had an avid interest in chess, followed the popular column by George Koltanowski in the San Francisco Chronicle and incorporated a shift move into his encoding of the 340 cipher, that required a knight's move to unlock its secrets half a century later? Did the individual outlined below have an influence on the Zodiac Killer? The answer may lie in a newspaper article in the San Francisco Examiner on July 16th 1978, announcing the upcoming World Chess Championship beginning on July 18th 1978 with a match between ​Anatoly Karpov and Viktor Korchnoi, covered by guest speaker George Koltanowski at the Paul Masson Vineyard in Saratoga, Santa Clara County. A county where only 3 months earlier, the Zodiac Killer may have mailed the April 24th 1978 "I am back with you" letter from.   

George Koltanowski, the legendary grandmaster of chess who wrote more than 19,000 chess columns for The San Francisco Chronicle with the same ease with which he dispatched countless opponents in a career that spanned 10 decades, died Saturday (February 5th 2000) in a San Francisco hospital after a brief illness. He was 96. His column, which appeared in The Chronicle every day without interruption for 52 years, was the longest-running daily chess column in history.

He was also the world champion of a form of the game known as blindfold chess, in which the player commits the game to memory and does not look at the board or touch the pieces used by opponents, who play in the normal fashion. Mr. Koltanowski's 1937 feat of playing 34 opponents simultaneously while blindfolded without losing a game has never been equaled. Koltanowski was the former president of the U.S. Chess Federation, which bestowed upon him the title of "Dean of American Chess." He served during the years after the Bobby Fischer boom of 1972, when interest in chess soared to record highs after the mercurial American grandmaster won the world title. Koltanowski seized the momentum of those heady days to install chess clubs in countless schools, community centers and even at San Quentin Prison. San Francisco Chronicle.

Among his countless chess feats, Mr. Koltanowski was well-known for performing the Knight's Tour, where random bits of information such as names and phone numbers would be supplied by audience members and written in the 64 squares of a giant chessboard. In seconds, Mr. Koltanowski would commit the entire hodgepodge to memory. Then, while blindfolded, he would call out the intricate path required for a chess knight to make its series of L-shaped hops around the board -- by recalling the scraps of information in order.  ​If the Zodiac Killer had a liking or fascination with chess and puzzles, he would very likely have known about the knight's tour challenge, a mathematical problem where you have to move a knight around a chessboard (8 X 8 grid) and visit all 64 squares without landing on a square more than once. The Knight's Tour is very well-known, recognized as a classic, over-thousand-year-old mathematical puzzle and graph theory problem, first appearing in 9th-century Sanskrit texts and later analyzed by Leonhard Euler, becoming famous for its complexity and links to magic squares, popularizing it through chess history and computer science as an illustration of algorithms. ​

To commemorate the opening of the World Chess Championship in the Philippines on July 18th 1978, George Koltanowski appeared at a chess tournament in the Paul Masson Vineyard in Saratoga, Santa Clara County, which offered $15,000 in prize money and was open to 700 players. A chess tournament was held there annually in the late 1970s and early 1980s. The San Francisco Examiner newspaper reported on July 16th 1978 that it had not yet been decided whether George Koltanowski would be performing his mind-blowing Knight's Tour chess puzzle while blindfolded, or would be taking on the Controlled Data's computer in St. Paul Minnesota, while sitting in the shade of the sycamore trees in the Paul Masson Vineyard in the mountains of Saratoga.

Whatever the case, the day after the World Chess Championship began (and while George Koltanowski was giving his performance in Saratoga), the Zodiac Killer mailed a letter to the San Francisco Chronicle on July 19th 1978, stating "But maybe you play chess with me. I have several cheap sets in closets all over. I have my name on the bottom of the lid with the scotch tape....My tape is waiting for me all over California". Clearly this was no coincidence, especially when you consider that this Zodiac letter was probably composed on July 18th 1978, the day the World Chess Championship began, the day that George Koltanowski gave a talk in Saratoga about the opening chess match between Anatoly Karpov and Viktor Korchnoi, and the same day that the Santa Cruz Sentinel (and numerous others) reported on this very same chess game, with a Zodiac Killer newspaper article right next to it, entitled "SF Chief Says Inspector Didn't Write Zodiac Letter". A newspaper article on July 18th 1978 about David Toschi who had been demoted to pawn detail, followed by a Zodiac letter on July 19th 1978 inviting the former inspector to "maybe play chess". 

In the Zodiac Killer letter postmarked July 19th 1978, it stated "I am the ZODIAC and I am in control of all things. I am going to tell you a secret. I like friction tape. I like to have it around in case I need to truss someone up in a hurry....I have my real name on a small metallic tape. You see, while you have it in your possession, I want you to know it belongs to me and you think I may have left it accidentally. I am athletic. It could be swim fins, or a piece of scuba gear. But maybe you play chess with me. I have several cheap sets in closets all over. I have my name on the bottom of the lid with the scotch tape....My tape is waiting for me all over California. Do you know me? I am the ZODIAC and I am in control". You will notice that the letter mentions Scotch Tape, invented in 1930 by 3M engineer Richard Drew in St. Paul, Minnesota (and manufactured there). The very location of the computer being challenged by George Koltanowski at the time the Zodiac Killer letter arrived at the San Francisco Chronicle, mentioning chess. Designed as a moisture-proof sealant for food packaging, it quickly became popular during the Great Depression for repairing household items. The Zodiac Killer informed us that he had his name "on the bottom of the lid with the scotch tape", leading many to believe that the Zodiac Killer's name may have been "Paul", contained within the location of St. Paul, Minnesota. 

Is it possible that the Zodiac Killer attended this chess tournament at the Paul Masson Vineyard in Saratoga as a competitor or spectator? This location is situated 2 miles (by crow) from where Kathy Bilek (18) was stabbed to death on April 11th 1971 in the woods of Villa Montalvo, whom the Zodiac Killer claimed responsibility for on July 13th 1971 by mailing the "Monticello" card, stating "Near Monticello Shought Victims 21 ...... In The Woods Dies April". Saratoga is close to San Jose, which has consistently featured in the Zodiac Killer story.

The company (3M) that produced Scotch Tape also invented Post-it Notes (sticky notes) in 1974. George Koltanowski famously used sticky notes (or small pieces of paper) as part of his demonstration of the "Knight's Tour" during his exhibitions. During his demonstration of the knight's tour, George Koltanowski would ask audience members to call out random words, names, or numbers, which were written on sticky notes and placed on each of the 64 squares of a large demo chessboard. He was then blindfolded, and another person would select a random square. Starting from that square, Koltanowski would recite the text on the note and continue to call out the contents of every other square in sequence, without error, following the path of a knight's tour until all 64 notes were removed. A knight's move that was required to solve the Zodiac Killer's 340 cipher, mailed to the San Francisco Chronicle where George Koltanowski had a chess column. The audience members sometimes had their names placed on sticky notes, not unlike the Zodiac Killer, who claimed his name was on Scotch Tape all over California. 

The Scotch Tape letter upon first reading makes little sense, but everything contained within Zodiac communications usually have their foundation in Bay Area newspapers, which the Zodiac Killer borrowed from and inserted, often cryptically, into his writings to the San Francisco Chronicle (and occasionally others). Whether this extended to the 340 cipher through an interest in chess, is open to question.    

FURTHER READING: A PAWN IN A GAME OF DEATH

It is almost impossible to forge a solid connection to the Zodiac Killer from the Riverside communications, despite some interesting parallels, such as the trinity of letters mailed to the Riverside Press-Enterprise, Riverside Police and Joseph Bates in 1967 (and the Confession letters), foreshadowing a similar methodology in the Bay Area of northern California, with communications to the Vallejo Times-Herald, San Francisco Chronicle and San Francisco Examiner. Both sets of letters possibly containing the letter "Z" and giving us a common thread to "The Most Dangerous Game" and Count Zaroff of yesteryear.

​The two Confession letters mailed in 1966 stated "I am not sick. I am insane. But that will not stop the game" and "I am stalking your girls now", and offered us a message reminiscent of the flawed character traits of Count Zaroff and Erich Kreiger (A Game of Death, 1945), who were insane, heartless, and psychopathic men with a thirst for stalking and hunting human beings. The question being, were the Confession and Bates letters a precursor to the arrival of Zodiac on July 31st 1969, who boasted that "it was more fun than killing wild game in the forest because man is the most dangerous animal of all". A "game" that was played in Riverside, Benicia and Vallejo - and would continue into the middle half of 1971, with the "Z" of Count Zaroff seemingly never far away. 

The Zodiac Killer should have been unaware of the Bates letters in 1969 (and what some believe is a stylized "Z" signature), had he not been the author, so it may be noteworthy to point out the possibility of the 408 cipher being signed with the identity of "Z", present on the ring of Count Zaroff in "The Most Dangerous Game" (1932). The Zodiac Killer used the exact phrase uttered by Merian C. Cooper, the associate producer of the movie, when interviewed just prior to its release, by encoding the the words "man is the most dangerous animal of all" in his 408 cipher. So would it really be that unusual if he also encoded the letter "Z", taken from the main protagonist and big game hunter, in a story of unbridled madness? 

It is fairly clear that the Zodiac Killer made an error when taking his draft 408 message and separating it into three parts, missing out one complete row of seventeen characters when moving between his letters to the San Francisco Examiner and San Francisco Chronicle. The message on rows 17, 18 and 19 all began with the plaintext letter "E", so it is perfectly easy to comprehend how the Zodiac Killer accidentally skipped one row and left himself with 18 unwanted spaces rather than one. This is where I believe he intended to place his identity of "Z", synonymous with the villainous Russian aristocrat, Count Zaroff, who also enjoyed killing people for nothing more than entertainment.

On the left is the message he likely intended to encode, leaving us with "AFTERLIFEE" at the end of his cipher. The Zodiac Killer placed a dotted circle in the 391st position to give us the extra "E" in afterlife, so one could argue this was supposed to originally complete the 408 cipher and be the signature we had to work out. Only when the cipher key was understood, did it become apparent that the initial ciphertext character to represent the letter "E" in his cipher key was "Z". Whether this was the Zodiac's thinking is unclear, but the evidence is fairly compelling that he never intended to leave us a garbled message of 18 characters, that nobody has come close to explaining in over half a century. The massively interpretative quality of 18 jumbled letters should absolutely tell you that no definitive solution could ever be satisfactorily proven to be the correct answer - and as such - was never the intention of the Bay Area murderer, who was certainly no dummy. But the letter "Z" was, without doubt, an identity he would employ in later communications, with one additional key ingredient always present. This would show itself on October 27th 1970, when the Zodiac Killer selected his Halloween card with a specific message.       

The author of the typed Confession letters on November 29th 1966 claimed their insanity would "not stop the game" of murder, with the Zodiac Killer on July 31st 1969 bragging that killing people was "more fun than killing wild game in the forest", by taking his cues from "The Most Dangerous Game" (1932), where the letter "Z" both down south and up north, may have been the signature. Then came the Halloween card on October 27th 1970, in which the Zodiac Killer addressed Paul Avery and selected a card with the message "But, then why spoil our game", while visibly adding the letter "Z" to a communication for the first time, just 20 days prior to the Paul Avery article on November 16th 1970, informing us of the Bates letters from 1967 with a Z-like signature. Seven months later, another letter and cryptogram of 148 characters would be mailed to the San Francisco Chronicle newspaper, carrying the message "man is the most prized game", taken straight from the playbook of General Zaroff and "The Most Dangerous Game". This letter was signed with a sun cross, the ciphertext character representing the letter "Z" in the cipher. The Zodiac Killer only utilized the word "game" in three communications, on July 31st 1969, October 27th 1970 and May of 1971, with the letter "Z" plausibly embedded in the coding of two, and clearly present in a third. If the Zodiac Killer authored the communications in Riverside, it's possible he added a fourth - and may very well have been correct when he stated his insanity would "not stop the game", as many investigators had the misfortune to find out. 

Richard Connell book, The Most Dangerous Game (1924): "My dear fellow," said the general, "have I not told you I always mean what I say about hunting? This is really an inspiration. I drink to a foeman worthy of my steel--at last." The general raised his glass, but Rainsford sat staring at him. "You'll find this game worth playing," the general said enthusiastically." Your brain against mine. Your woodcraft against mine. Your strength and stamina against mine. Outdoor chess! And the stake is not without value, eh?"

Thanks to the recently unveiled FBI files regarding the disappearance of Donna Lass (25), last seen at the Sahara Tahoe Hotel & Casino on September 6th 1970 at 2:00 am, it is safe to say that Donna Lass was not abducted from the casino (or its parking lot) at the end of her shift, and didn't meet foul play by the hands of a random stranger, who intercepted her journey while she returned back to her apartment in the early morning hours (whether she was walking or in a vehicle).

Donna Lass had changed out of her nurse's uniform and into a navy blue slack suit shortly before her shift end at 2 am. These were the clothes the young woman was last seen wearing at the Sahara Tahoe Hotel & Casino, that were not found in her apartment by investigators, which may lead some to believe she never arrived home that morning. However, her purse (handbag for carrying personal items) was discovered in her apartment, containing money, her personal cosmetics and car keys, which almost certainly suggests she returned back to her home after leaving the casino. She may have walked home, or accepted a lift from somebody at the casino (or during her journey), but the important thing to remember here, is that her navy blue slack suit was missing, yet her purse wasn't. A blue purse in possession of Donna Lass was noted by somebody at the Sahara Tahoe Hotel on September 5th 1970 (color coordinated with her blue dress and blue shoes), and a purse was described by investigators at her apartment containing her check book, car keys, personal cosmetics and a wallet containing less than $25. This was very likely the same purse seen by the individual at the Sahara Tahoe Hotel - again suggesting she arrived home safely in the early morning hours of September 6th 1970.

Her 1968 Chevrolet Camaro was found outside her Monte Verdi apartments on 3893 Pioneer Trail Road by the South Lake Tahoe Police Department on September 13th 1970, which suggests, that had she met foul play that morning, we are still unable to rule out that she drove to work on September 5th 1970, and returned home in her car on September 6th 1970, knowing now her car keys were found in her purse inside the apartment. In absence of any confirmed sightings of Donna Lass after 2 am on September 6th 1970, the fact that her navy blue slack suit was never seen again, strongly indicates she didn't change out of these clothes after arriving home that morning. Especially when we consider a malicious phone call was received by the Sahara Tahoe Hotel & Casino on September 7th 1970, claiming falsely that Donna Lass had been called out of town for a family illness and would not be returning to work for a few days. This obviously means that Donna Lass met foul play between the time she returned to her apartment on September 6th 1970, to the time the malevolent call was made to the casino the following day (September 7th 1970). And it tells us that she never likely removed her navy blue slack suit and went to bed.

The private investigator's report stated that the mysterious caller identified himself as Mr. Davis (Donna's new landlord), which Nick Davis vehemently denied was him. It would have been extremely stupid to have murdered Donna Lass and then used your own name to excuse her absence due to family illness, that obviously would have been discovered in due course by investigators. If this was the case, the caller wasn't Nick Davis. But this detail about "Mr. Davis" was not mentioned in the FBI files, which only referred to the phone caller as an unknown male. Even if the caller mentioned no name, it is clear that this person was involved in the disappearance (and likely murder) of Donna Lass, who knew where she worked, and felt the need to buy time and phone the casino to excuse her absence.

A random killer (unknown to Donna Lass and living distant from her residence), who murdered her at the apartment or abducted her from it, has absolutely no need to make contact with the Sahara Tahoe Hotel & Casino and make a bunch of excuses. The only person who needs to buy time is somebody the police would have chosen to visit first, such as friends, neighbors  and work colleagues. Somebody who may have given Donna Lass a lift in the early hours of September 6th 1970, somebody who rode in her vehicle that morning, or somebody that visited her apartment after she arrived home from work. Somebody that killed or abducted her while she was still wearing her navy blue slack suit, who needed to confuse the timeline of her disappearance and murder. The clothes she left work in vanished alongside her, but her purse, that she almost certainly carried with her when she arrived at work on September 5th 1970, found its way back to her apartment on September 6th 1970.

​It appears as though Donna Lass met her demise shortly after leaving work and arriving home. Was it a co-worker or a resident at the Monte Verdi apartment complex at ​3893 Pioneer Trail Road? The final question is why did the "killer" make the phone call on September 7th 1970 and inform the casino that Donna had gone out of town, rather than phoning her workplace in the daytime hours of September 6th 1970. Was he aware that Donna Lass wasn't working on the evening of September 6th 1970, and had the day off? There can't be many other reasons why the perpetrator waited over 24 hours to phone the casino. If this was the reason, it may narrow the focus to somebody who was not only familiar with her profession, but to somebody who knew her work schedule, such as a friend or close work colleague. A person who didn't want this crime investigated as a murder and needed to make the body disappear.  

A KILLER FROM THE CASINO [PART ONE]     A KILLER FROM THE CASINO [PART TWO]

For five years, since the 340 cipher was cracked by David Oranchak, Sam Blake and Jarl Van Eycke, people have been under the misconception that the Zodiac Killer made many mistakes when encoding his 340 character message, but the reality is almost certainly different, with only eight mistakes yet to be fully explained in his cipher. I have found only four mistakes in the first 9 rows, and the same number in the second 9 rows, giving us eight mistakes in 340 operations during the encoding process, which is a success rate of 97.65%. The Zodiac Killer upped the level of difficulty from the 408 cipher to the 340 cipher, probably in response to the speed his first offering was cracked. However, no one likely expected the Zodiac Killer to ramp up the difficulty level from the first 9 rows to the second 9 rows in this one cipher. He clearly overestimated its complexity, because the message he masked behind a wall of ciphertext was of a contemporary nature, intended to be read in 1969 or 1970, not half a century later. The notion purveyed of a killer who bumbled his way through the 340 cipher, losing concentration numerous times during the encipherment process, can now be utterly dispelled. This cipher was as devious as it comes.  

The Zodiac Killer made the 340 cipher more difficult by using a combination of substitution and transposition to disguise his message, but he added a third layer in the second 9 rows of the cipher by adding 14 deliberate spelling mistakes in an organized pattern 9 spaces apart (running diagonally across the cipher). The Zodiac Killer not only hid his message by using a 9 shift (and negative 8 shift) technique shown here, but he would further complicate matters for codebreakers by baking in these spelling mistakes using the same 9 shift technique. If you thought that was the last hurdle codebreakers had to overcome you would be mistaken, because a fourth layer was added, also 9 spaces apart in a diagonal pattern. The Zodiac Killer placed the phrase "LIFE IS" into his message {blue rectangles), inserted deliberately into certain positions so that it would appear at the end of the 10th row of the original 340 cipher when the key was applied. Below are the 14 deliberate spelling errors he placed into his message, running diagonally across the grid (red rectangles). The four green circles, I believe, are the accidental errors made by the Zodiac Killer. These concepts were fully explained in the previous article No Cipher Mistakes by Zodiac. 

Below is the Zodiac Killer's encoded message with the spelling errors rectified (in brown). There is absolutely no way the Zodiac Killer accidentally made these 14 mistakes in such an organized pattern. If you add the "LIFE IS" phrase into the mix (blue rectangles), it gives us 20 deliberate "errors" by the Zodiac Killer, all organized diagonally 9 spaces apart.

This leads us to the Zodiac Killer's next "13-Symbol" cipher mailed on April 20th 1970, in which the Zodiac Killer introduced the code with the phrase "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is....". If we had cracked the last cipher he sent us, we would have known that the message was encoded behind a simple combination of 9 and 8 shift techniques, which if applied to the 13-Symbol cipher encodes the message of "ME ⊕" ("ME" followed by the Zodiac crosshairs). Simply traveling 8 positions to the right of each circled 8 and cycling through the 13​-Symbol cipher, gives us the "identity" of "ME ⊕". A signature twice highlighted in the Halloween card on October 27th 1970, and given to us directly by the Zodiac Killer in the Exorcist letter on January 29th 1974. All these three communications teased us with the promise of a name, and all can easily be shown to give us the signature of "Me" in their design. The personal pronoun of "ME" was synonymous with the pseudonym "Zodiac" and his "crosshairs", hence the use of "Me-37" in his Exorcist letter rather than "⊕-37", a format he usually chose. Was the Zodiac Killer playing one big joke on us all? See here.

The Zodiac Killer's 340 cipher was broken up into 3 parts of 9, 9 and 2 rows. This was the initial key to solving the 340 cipher. If we apply the same methodology across the Z13 and cycle through the code (9th, 18th and 20th positions), we get 888, the key to solving the Zodiac Killer's 13-Symbol cipher. See here.

The first 18 rows of the 340 cipher reads I HOPE YOU ARE HAVING LOTS OF FUN IN TRYING TO CATCH ME - THAT WASN’T ME ON THE TV SHOW - WHICH BRINGS UP A POINT ABOUT ME - I AM NOT AFRAID OF THE GAS CHAMBER BECAUSE IT WILL SEND ME TO PARADICE ALL THE SOONER BECAUSE I NOW HAVE ENOUGH SLAVES TO WORK FOR ME WHERE EVERYONE ELSE HAS NOTHING WHEN THEY REACH PARADICE - SO THEY ARE AFRAID OF DEATH - I AM NOT AFRAID BECAUSE I KNOW THAT MY NEW LIFE IS. It is clear that the first 9 rows of the cipher (in black) carried the important part of Zodiac's message, where he confirms that it wasn't him on the TV show, and he was not afraid of the gas chamber. However, the second part of his message (in blue) is pretty irrelevant drivel about "paradice" and "slaves", copying much of what was present in the 408 cipher. This may be the reason the Zodiac Killer created the first 9 rows of the cipher with less complexity and without the designed spelling mistakes present in the second 9 rows. He probably cared less about the second part of his message being deciphered. The amount of cleverness baked into the 340 cipher shows that the Zodiac Killer knew perfectly well that the design of the Z13 and Z32 codes were incompatible with normal cryptographic techniques using all the ciphertext, which is why anybody adopting this approach is quite frankly wasting their time. These two codes require a much more nuanced approach, along with an in depth knowledge of the Zodiac case spanning several years..

THE INSERTION OF THE CORRECT PLAINTEXT LETTERS BELOW WOULD RECTIFY 78% OF THE MESSAGE. ONLY FOUR ERRORS WOULD REMAIN (THE GREEN CIRCLES). 

BELOW ARE THE SECOND 9 ROWS OF THE ORIGINAL 34O CIPHER WITH THE CIPHER KEY APPLIED. THIS IS BEFORE THE PERIOD 19 SHIFT WAS USED IN AN ATTEMPT TO FIND A COHERENT MESSAGE.