The Zodiac Killer may have been inspired to switch from gun to knife after the extensive front page coverage given to the murders of Debra Gaye Furlong (14) and Kathy Ann Snoozy (15), who were found murdered on August 3rd 1969 in the Bay Area of San Jose. They were savagely attacked with a penknife. The chief medical examiner described the ferocity of the attack: "Dr. Hauser, so shaken by the brutality of the crime he could scarcely find words, said the Snoozy youngster had 150 wounds on her back, 50 on the front and a "storm" of punctures on her neck. Deborah's body had about 100 wounds on her back and upper front and a dozen on her neck". Disillusioned by his lack of front page coverage, the Zodiac Killer struck in Lake Berryessa on September 27th 1969 inflicting 16 knife wounds on the defenseless Bryan Hartnell and Cecelia Shepard. He would write on the card door of Bryan Hartnell's vehicle minutes after the attack, stating Vallejo 12-20-68, 7-4-69, Sept 27-69 -6:30 by knife. On November 8th 1969 he would not only claim the murder of Cecelia Shepard, but the murders of Debra Furlong and Kathy Snoozy in the August of 1969, writing Des, July, Aug, Sept, Oct = 7 on the greeting card. 

Just thirteen days after the mailing of the 'Dripping Pen' greeting card, the Zodiac Killer would write another cryptic message on November 21st 1969 - this time to the San Jose Police Department (the city of the Snoozy and Furlong murders), bumping up his running victim total to November = 8 and beginning the message with "There's no doubt I will do my Thing!". Bearing in mind the Zodiac Killer had switched to a knife at Lake Berryessa to achieve "front page coverage", and claimed the savage knife murders of two teenage girls, who had both been stabbed in excess of 100 times, the Zodiac Killer's claimed 8th victim should mirror these attacks. If he was going to keep up the terror in the minds of the American people, the 8th victim would likely have been murdered in California just prior to the mailing of the November 21st 1969 letter - and stabbed multiple times. 

Although unidentified until 2016 and known only as Jane Doe 59, Reet Jurvetson (19) was discovered on November 16th 1969 by Trevor Santochi, who was hiking on Mulholland Drive in Los Angeles. Reet Jurvetson had been viciously stabbed in excess of 150 times by a common penknife in the neck, chest and torso, similar to the attack on the two teenage girls from San Jose. Close to her body in the ravine next to the road, a pair of black prescription glasses (Liberty brand frames) were discovered. Detectives have concluded they are likely connected to her death. The Zodiac Killer was extremely unlikely to have been responsible for her murder, but just like the vague clue of "Aug" on November 8th 1969 insinuating his involvement in the penknife attack on Snoozy and Furlong, was he similarly giving us the vague clue of November = 8 to suggest his involvement in another senseless penknife attack just five days earlier? Had he read about the discovery of Reet Jurvetson's murder in the newspapers - the similarities between the two crimes of which would not have gone unnoticed.   

On October 20th 1969, nine days after the murder of Paul Stine in Presidio Heights, somebody made a threatening phone call to the Palo Alto Times newspaper saying he intended "to pick the kids off as they get on the school bus". The San Bernardino County Sun reported on the threat, stating "Patrol cars convoyed school buses around Palo Alto yesterday after a telephoned murder threat by a man claiming to be the Zodiac Killer of five persons. The weird slayer who signs himself "The Zodiac" made a similar threat in a letter to the San Francisco Chronicle last week after the Oct 11 shooting of a taxi driver. The district transportation supervisor said an armed guard might ride with each of the system's 25 buses. Officers in Napa and Vallejo, areas of the first three murderous attacks, some 45 miles north of Palo Alto, have been convoying police officers. Palo Alto Police Chief William Hydie called the new threat "extremely serious," but warned against over reaction to what might be a crank call".

On November 8th 1969, the Zodiac Killer mailed the 'Dripping Pen' card and 340 cipher to the San Francisco Chronicle claiming the "Aug" murders of Debra Gaye Furlong (14) and Kathy Ann Snoozy (15), who were found brutally stabbed on August 3rd 1969 in the Bay Area of San Jose.

On November 21st 1969, somebody claiming to be the Zodiac Killer wrote to the San Jose Police Department​ threatening the life of a widow, accompanied by the words "There's no doubt I will do my Thing". The brief text in the letter clearly contained enough information for police to identify the woman and implement 24-hour surveillance on her residence.

On December 7th 1969, a letter was mailed from Fairfield stating "I just need help. I will kill again, so expect it any time the will be a cop".

On December 16th 1969, another letter arrived from Fairfield threatening to kill "government life" and "cops" in Sacramento, Fairfield, Napa, Vallejo, Oakland, San Francisco and San Jose. A future geographic profiling technique was applied to the locations in which he 'threatened murder' (as detailed in the Fairfield letter), and noted that "Interstate 80 begins at an interchange with U.S. Route 101 (US 101) in San Francisco, and then crosses the San Francisco–Oakland Bay Bridge into Oakland. It then heads northeast through Vallejo, Fairfield, Sacramento, and the Sierra Nevada mountains before crossing into Nevada". The idea was to identify the areas the Zodiac Killer was prepared to target, based on their accessibility to him using a main commuter route he regularly traveled. If he regularly used the I-80 for his profession, then six of these seven destinations are directly passed by the I-80, with Napa only a few miles off route.

On December 19th 1969, somebody claiming to be the Zodiac Killer again threatened cops, making a phone call to Sergeant Robert Rengsdorff of the San Jose Highway Patrol (see article above), stating "I am going to kill five of you officers and a family of five between now and Monday". This threat towards San Jose police and a family of five was issued on a Friday, exactly as was the November 21st 1969 letter, mailed to San Jose police threatening harm on a widow. After the threat on the widow was thwarted by 24-hour police surveillance on her residence, was this the response, to once again instigate fear in the San Jose community? Were the widow and 'family of five' of the same residence? We know he was threatening the lives of numerous police officers, but the threat on five members of a family appears rather specific.           

On December 20th 1969, the Zodiac Killer mailed the 'Melvin Belli' letter containing a piece of murdered Paul Stine's shirt, effectively proving the author was the murderer of the taxicab driver on October 11th 1969. This letter mimicked the December 7th 1969 Fairfield letter by stating "please help me", which in some way helps to authenticate both Fairfield letters not released to the newspapers.

​The purpose of this article is to show the targeted areas of the Zodiac Killer (if responsible for these letters and phone calls) from the standpoint of geographic profiling. These events spanned from the October 11th 1969 murder of Paul Stine, to the mailing of the 'Melvin Belli' letter on December 20th 1969 (71 days). The areas shown in red above, highlight the locations the Zodiac Killer targeted by murder, proposed murder, as well as by his threatening phone calls and letters - and they are all connected by one direct route of travel.

During these 71 days in October, November and December the Zodiac Killer focused his attention on Sacramento, Fairfield, Vallejo, Oakland, San Francisco, Palo Alto and San Jose. Interstate 80 and U.S. Route 101 provide one seamless journey from Sacramento to San Jose. Was the Zodiac Killer a traveling salesman which took him through each of these locations - and therefore he had a familiarity with? Do these commuter route tell you anything about his home residence during this time period? 
When you commit, or intend to commit these acts, accessibility to and from a main commuter route could be invaluable.

Equidistant (as the crow flies) to Sacramento and San Jose is the waterfront city of Vallejo, believed by many to be the home residence of the Zodiac Killer. It is 53 miles from Sacramento and 57 miles from San Jose. The Springs and Tuolumne payphone, where Zodiac placed a call to police dispatcher Nancy Slover on the morning of July 5th 1969, sits 728 metres from Interstate 80.

Using old and new material, we will take a comprehensive look at the 'Dripping Pen' card mailed by the Zodiac Killer on November 8th 1969, and attempt to link it to a future threat of murder. The card itself was most likely chosen for purpose, referencing the immediate aftermath of the attack on Bryan Hartnell and Cecelia Shepard at Lake Berryessa on September 27th 1969. Approximately five minutes after the brutal stabbing, the killer walked to the side of Bryan Hartnell's white Volkswagen Karmann Ghia and wrote "Vallejo 12-20-68, 7-4-69, Sept 27-69 -6:30 by knife". The hand the killer wrote on the car door with, was likely the hand he used during the attack on the young couple, almost certainly peppering his dominant hand with blood, and consequently to the marker pen he wrote with. So, the choice of greeting card stating "Sorry I haven't written, but I just washed my pen" was likely a sardonic reference to the callous and bloody attack at Lake Berryessa. The addition of "Aug" on the card inner, a suggestion of his involvement in the double murder of Deborah Furlong and Kathy Snoozy in San Jose on August 3rd 1969. This, coupled with the footnote of "by knife" written on the car door, was likely deliberately engineered to steer investigators toward this conclusion. They had after all considered this premise in the October 1st 1969 edition of the San Francisco Examiner, in which was stated "And today San Jose police, to the south, inquired of law enforcement officers here whether there was indication that the "Cipher Killer" might be linked to the knife slaying of two teenage girls Aug.3, still unsolved". This wouldn't be forgotten by the Zodiac Killer.   

Another reason to believe the 'Dripping Pen' card was referring to Lake Berryessa can be found in its design. The Zodiac Killer, almost without exception, would give us a running total of his victims, occasionally writing the victim count on the horizontal wing of the crosshairs. The only two times this was not the case, was the November 8th 1969 'Dripping Pen' card and the car door of Bryan Hartnell's white Volkswagen Karmann Ghia. In both of these writings he gave us his Zodiac crosshairs with the months of his murders underneath. This was the first and last time he would ever do this.

If you run the message from the face of the 'Dripping Pen' card to inner, it reads "Sorry I haven't written, but I just washed my pen and I can't do a thing with it". So, when the Zodiac Killer wrote "I get aufully lonely when I am ignored, so lonely I could do my Thing", he was indicating that in the future when he needed some attention, he would write again. His Thing being his propensity to put pen to paper, or in the case of Lake Berryessa, to metal. He was effectively addressing the police when he wrote "I though you would need a good laugh before you hear the bad news. You won't get the news for a while yet". In fact, the bad news would arrive in exactly thirteen days time - and it was directed towards the police in regards to the month of August. In effect, his next correspondence would be pushing the same narrative as the car door and greetings card, of his involvement in the deaths of Deborah Furlong and Kathy Snoozy. 

​On November 21st 1969, a letter arrived at the San Jose Police Department, addressed to a particular law enforcement officer. The letter was threatening a widow - so much so - that police initiated 24-hour surveillance on the woman's home. The police stated that "they believed the widow in the message may be Mrs......" In other words, the woman wasn't directly named in the correspondence, but they had by reasonable deduction, concluded who the threat was aimed at. I believe that the Zodiac Killer, in his continued drive to cement the notion of his involvement in the two teenage girls murders, mailed this "bad news" to the San Jose Police Department. Can it really be a coincidence that he wrote "by knife" on the car door to plant the seed, added the "Aug" on the 'Dripping Pen' card, then mailed his next correspondence to the City of San Jose? In addition, this new communication began with some familiar words: "There's no doubt I will do my Thing".  

On November 21st 1969, the San Jose Police Department would still have been devoting many hours to the unsolved murders of these two teenage girls, and likely receiving many tips from potential eyewitnesses and the residents of San Jose, eager to assist in the investigation. What better way for the Zodiac Killer to convince law enforcement of his potential involvement in this crime, by threatening to do his Thing on one of these residents.

I have no doubt the Zodiac Killer was scouring the newspapers about this crime - so imagine he came across such a headline:
"An elderly widow, Maureen Jones, was today helping police with their investigation into the senseless murders of two young girls in San Jose, Sergeant Johnston said", or "An elderly widow, residing at Seacreek Way, was today helping police with their investigation into the senseless murders of two young girls in San Jose, Sergeant Johnston said". These article excerpts are fictitious, designed to show what Zodiac  may have read in any number of articles I have no access to. 

The Zodiac Killer never mentioned his victims by name, so it is entirely plausible that whether he knew this woman's name or not, he could, by sending a threatening letter to police using the term "widow", and addressing the communication to "Sergeant Johnston", convince police that the threat was a credible one. This may be why the police believed they knew who the woman was, despite the fact her name was never mentioned in the correspondence mailed to the San Jose Police Department. Because she had recently received newspaper coverage.     

A small code arrived with the November 21st 1969 communication. The short code (shown above in the FBI files) was
​-- + 6 2 + --, containing two dashes either side, two pluses, and the numbers 6 and 2. The idea that anybody looking at this code could arrive at 1620, without having previous reason to suspect this four number solution, seems unlikely. But if investigators knew that "Maureen Jones" lived at a residence, such as 1620 Seacreek Way, San Jose, then they might have reason to believe this is what the code was implying. Earlier newspaper reports stated "A killer armed with a thin-bladed stiletto was hunted here today as the one who savagely stabbed to death two teenage girls yesterday as they picknicked in Almaden Valley. The scene where the bodies were found is just south of Blossom Hill Road, two blocks west of Calahan in the northern end of the valley. About 10:00 am yesterday, the girls packed a lunch and left Deborah's parents' San Jose home for a picnic atop a grassy knoll nearby. The picnic ground is a rugged area, near a narrow, serpentine trail used by motorcyclists for hill-climbing contests".  So, if we could find a 1620 residence in San Jose, possibly close to the crime scene, this may be the location of the "widow" Zodiac was targeting.

As shown above, in the October 1st 1969 San Francisco Examiner article, "San Jose police, to the south, inquired of law enforcement officers here whether there was indication that the "Cipher Killer" might be linked to the knife slaying of two teenage girls Aug.3".  Therefore, would it really be that surprising if the Zodiac Killer had capitalized on their suspicions and mailed a threat to the San Jose Police Department? He knew he would be taken seriously by police - and why they were prepared to instigate 24-hour surveillance on the residence of the "widow" mentioned in the letter.

Thirteen days after the Zodiac Killer mailed the 'Dripping Pen' card and 340 cipher on November 8th 1969, another letter and code purporting to be from the Bay Area murderer was mailed to the San Jose Police Department on November 21st 1969, possibly containing a threat on a "widow" in the San Jose area. Both mailings have so much in common, along with the December 7th and 16th 1969 Fairfield letters, which also contained rudimentary codes. The Zodiac Killer wrote the chronological months of his murders at the foot of the 'Dripping Pen' card: "Des, July, Aug, Sept, Oct = 7". Bearing in mind that all but August were accounted for, it is now clear the card was inferring the murders of two young girls, Deborah Gaye Furlong (14) and Kathy Ann Snoozy (15), who were found savagely stabbed on August 3rd 1969 in the Bay Area of San Jose. It is therefore no surprise that his next communication should be focused on San Jose just two weeks later. Below is part of the FBI file revealing some of its contents.

Placing "November=8" could be viewed as an extension to his "Des, July, Aug, Sept, Oct = 7", indicating he was claiming another murder in November. He also began the communication with familiar words: "There's no doubt I will do my Thing". As the communication was mailed to the San Jose Police Department, we would now have three victims in San Jose to which he was laying claim to. The short code (shown above) was -- + 6 2 + --, containing two dashes either side, two pluses, and the numbers 6 and 2. Both Fairfield letters contained rudimentary codes pertaining to the 340 cipher, as though he was giving us a clue to its design. This may also have been the case when he mailed the Halloween card on October 27th 1970, intersecting the words Paradice and Slaves in a cross formation and writing "sorry no cipher" in similar fashion on the envelope. In fact, the December 16th 1969 Fairfield letter contained a design similar to the Halloween card. The 340 cipher can be shown to accommodate the words Paradice and Slaves, bisecting the cipher horizontally and vertically across its mid-section. This opened up the possibility that the San Jose code was somehow connected to this design. Both Fairfield letters harked back to the 340 cipher, so why not the San Jose code also.  

The symbols contained in the San Jose code exactly mirror the order shown on the horizontal mid-section of the 340 cipher. The 10th line is where some believe the cipher could be divided, along with the possibility of the word Slaves residing. Not only do the dashes and pluses line up exactly with the San Jose code using the mid-section of the 340 cipher, but the numbers 6 and 2 would slot nicely in between. If we used basic number play, and converted 6 to F and 2 to B, both these letters can be found together on the 10th line also. All six characters from the San Jose code present on the Slaves line of the 340 cipher. 

This may very well be coincidence, but with "There's no doubt I will do my Thing", "November=8" and this correspondence immediately following the 'Dripping Pen' card and 340 cipher, one could argue the Zodiac Killer was dropping us hints to the mechanics of his "crackproof" cipher. Something he would again do with the arrival of both Fairfield letters in December.

The Zodiac Killer could wait only one month after the Button letter, to give us further clues regarding the bomb he claimed to have buried, when he wrote "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". Why should the San Jose and Fairfield letters be any different?   

With extensive work done by AK Wilks on this topic, I would like to take a further look at the letter and code mailed to the San Jose Police Department on November 21st 1969. This came just ten days before the abduction of Elaine Davis from Walnut Creek on December 1st 1969. Her abductor traveling from the Bay Area, depositing her Navy peacoat just 26 miles south of San Jose, likely passing through it on his way to Light House Point in Santa Cruz. If the Zodiac was responsible for both letter and murder, then San Jose is a worthy avenue of interest. AK Wilks asked a pertinent question of the forum: "Does someone know of a recent murder case in San Jose that left someone a widow? Or a prominent widow who lived in San Jose in 1969? The police were seemingly able to determine who it was, so perhaps it was a well known case or person". The brief text in the letter clearly contained enough information for police to identify the woman and implement 24 hour surveillance on her residence. Was the author threatening to kill the 'widow' or abduct her from her residence?

The Zodiac Killer (or copycat) mailed a menacing postcard to Dr, Edward Adams in Orinda, California (near Walnut Creek) on October 12th 1970 stating "The Zodiac is going to change the way of committing murders. I shall announce when I shall commit my murders, The Adamses are Next you taught me to Mean it. ADAMS YOU ARE NEXT. ZODIAC."
As shown on the ZodiacKillerSite forum, Dr. Edward Adams and his wife featured in the newspapers prior to this threatening communication, so it is perfectly feasible that the author of the San Jose letter and code had identified his target in the days, weeks or months prior to the November 21st 1969 correspondence. Because of the nature of the redacted text, it appears that this letter was addressed specifically to a titled officer (possibly a Sergeant or Chief) of the San Jose Police Department. Bearing in mind the target of a 'widow' mentioned in the text, the author may be referring to a newspaper article involving the death of her husband, featuring commentary by the police official the letter is addressed to. The officer's name could be any number of characters in length depending on the title he holds, with the widow's surname just 5 or 6 characters in length. 
Was the widow a prominent member of society as suggested by AK Wilks, possibly a policewoman or politician, titled like Dr. Edward Adams. On December 16th 1969 the Zodiac Killer had set his sights on a cop or "government life". 

On the left is a December 22nd 1969 newspaper report from the San Mateo Times of somebody identifying himself as 'Zodiac' and threatening to kill five patrolmen and a family of five over the weekend, not dissimilar to his written threats in his trinity of July 31st 1969 letters: "I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend". 
The phone call was received on Friday December 19th 1969 by San Jose police dispatcher Shirley Searcy.

The disputed December 7th and 16th 1969 Fairfield letters (not published in the newspapers) both contained threats to murder cops for the first time, with the latter threatening to murder one policeman in San Jose. Three days later, this call to a San Jose Highway Patrol station threatening to murder police is remarkable timing. Was the caller responsible for both Fairfield letters - and more importantly - was it the Zodiac Killer?

I have searched high and low for the identity of this woman, but without a newspapers.com account to aid in the search I have failed to make any inroads. The author of the San Jose letter (if Zodiac) certainly didn't need a valid reason to target anybody, as shown by his murderous assault in the Bay Area, but the identity of the 'widow' could help to add legitimacy to both Fairfield letters mailed in December, dependent on her profession or previous relationship. The November 21st, December 7th and December 16th communications all contained short codes, the amateurish nature of which has led many to believe these three letters are the work of an impostor. But these features may actually bolster the argument for Zodiac involvement, as all three were never attempting to mimic the previously polished 408 and 340 cipher, which somebody attempting to mimic the Zodiac would surely have done.

UPDATE: THE DRIPPING PEN CARD AND SAN JOSE CONNECTION 
                 THE STORY OF SAN JOSE

On November 21st 1969 a suspected Zodiac letter was received.
The FBI file read: 'Re Butte tel to Bureau 11/21/69.
Enclosed herewith for the FBI laboratory are two copies of the letter received by (redacted) San Jose PD, San Jose, California on this date.
As noted, the message reads (redacted). 
The laboratory is requested to have the Cryptogram Section attempt to immediately decipher the message and furnish the results to the San Francisco Office.
For the information of the Bureau and Sacramento, after a cursory analysis, officers of the San Jose, California PD, believe widow in message may be Mrs (redacted), San Jose, California. San Jose PD instituting 24 hour surveillance on Mrs (redacted).'
A further page read:
11/24/69 - 'Copy of handprinted note beginning "There's no doubt I will do my Thing!" and ending with the symbol (drawn crosshairs). Results of examination:
The ciphertext portion of Qc33 is not readable using previously recovered key. Its brevity precludes further cryptanalytic examination at this time. The furnished interpretation of  "- + 62 + -" as representing "1620" can be neither proved nor disproved analytically. The = between "November" and "8" could represent the number "2". Such interpretation would be based on inferences drawn from the date of the postmark, not from cryptanalytic examination.'  (see below for FBI files).​ 

The FBI files ponder the idea of "November" and "8" being bridged by the number 2, possibly giving us November 28th, and therefore tying in with a presumed threat on a widow from San Jose. Here are some thoughts on Zodiac Killer Site forum. 
However, there may be a much simpler explanation, bearing in mind the Zodiac Killer's last two communications on November 8th and 9th of 1969- in particular the 'Dripping Pen' card.

That "November = 8" means exactly what it states- that the author or Zodiac is threatening, or has already claimed victim number 8 sometime in November.
​Bearing in mind the 'Bus Bomb' letter mailed on November 9th 1969 claiming 7 kills, then had an 8th victim already been claimed (presumably a male victim, if the mention of a widow was relevant), we would be looking for a victim between November 9th and November 21st. A future victim in November would likely have been murdered between November 21st and November 30th (the claimed target possibly being the woman in San Jose).
The phrase "There's no doubt I will do my Thing!" seemed to suggest an impending threat- hence the urgency of 24 hour surveillance on the woman. Thereby, the use of the term "widow" in the FBI file may likely not carry a sinister connotation of a prior murder.  
The Zodiac Killer was certainly looking for a ninth and tenth victim on December 20th 1969, when he mailed a further correspondence to Melvin Belli's residence.
​The reference to "- + 62 + -" appears to represent six characters rather than four, so is open to interpretation. 
Here is an aerial view of 2162 Ringwood Avenue, San Jose, Ca.  A code such as 2162SJ, coupled with a specific name would be enough. This is just a crude example, so any suggestions would be welcome.