The letter, including code is available on the right. Click the image to expand and once opened click a second time to magnify even further.
On April 20th 1970 the Zodiac Killer mailed a 13 symbol cipher to the San Francisco Chronicle, in addition to a bus bomb diagram threatening to blow up a school bus. The latter never materialized and the code has never been cracked, simply too short to verify any solution attained without a specific key. There have been hundreds of so called solutions to this code and most, if not all, are based on letter frequency or anagrams and as such cannot be discounted or proved, leaving us with only subjective interpretation.
The correspondence began;
"This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."
"I am mildly cerous as to how much money you have on my head now. I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station. Even though I talked about killing school children with one. It just wouldn't doo to move in on someone else's teritory. But there is more glory in killing a cop than a cid because a cop can shoot back. I have killed ten people to date. It would have been a lot more except that my bus bomb was a dud. I was swamped out by the rain we had a while back."
He also included the bus bomb diagram (see right). WORDING ON DIAGRAM
"The new bomb is set up like this. Sun light in early morning.
A + B are photoelectric swiches when sun beam is broken A closes circut "B opens "which makes B the cloudy day discon--ect so the bomb won't go off by accid. PS I hope you have fun trying to figgure out who I killed."
This diagram detailed how the Zodiac was prepared to blow up a school bus by remote control. It exhibits the use of an electronic eye, so that when the bus passes it breaks the beam and detonates at window height. Experts who have examined it have stated the bomb would function .
In the letter the Zodiac Killer was referring to the murder of San Francisco police officer Brian McDonnell on February 16th 1970, two months earlier, when a bomb exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. See here.
There are two characters in the code that have yet to be 100% determined. The three identical symbols at the center appear to be circled 8's, but an alternative has been suggested, that they could possibly be three circled Taurus symbols, and to their right an inverted Aries symbol. This carries some weight, after all, the Zodiac Killer may have chosen his moniker based on the 12 signs of the Zodiac horoscope, so including them in his ciphers may not be that unusual.
Harvey Hines, a retired law enforcement officer, pitched in with his theory on the cipher, regarding one of the high profile suspects in the case, that of Lawrence Kane. Harvey Hines, who retired from the California Police Department in 1992 had an avid interest in the Donna Lass case and remained resolute in his determination to solve her disappearance, forming close associations with the Lass family members. Along with Mary and Don Pilker, the sister and nephew of Donna Lass, they became convinced the Zodiac Killer was responsible for the abduction in South Lake Tahoe. Harvey Hines believed Lawrence Kane to be responsible for her abduction and likely murder and believed the '13 Symbol' cipher to contain the name 'Kane', clearly evident on the left hand portion of the cipher. The three 8's added up, he surmised was the killer's birth year. Lawrence Kane was born on 26th April 1924. To watch a video on this subject click here.
However this is a simplistic solution, that as stated above, could never be proven or disproven. What is certain though, is that anybody claiming a 100% solve without first finding the key is mistaken. One person who has dedicated his time and energy to the Zodiac ciphers is Dave Oranchak, and his site Zodiac Killer Ciphers is your first port of call when analyzing the various codes, why we are the 'most pattern seeking animal of all', and why almost invariably our solutions are flawed.
In many pages on this site we have discussed how the Zodiac Killer responded to the newspapers, sometimes within days, countering claims or supplying extra details about his crimes and this correspondence may be no different. Michael Cole, an avid Zodiac researcher, and host of the Zodiac website 'The Zodiac Revisited', produced an interesting article entitled 'My Name is Cipher Motivation,' showing where the inspiration for this correspondence lay. Here is a short excerpt, but to read the entire article follow the subsequent link provided;
"The article of interest, however, wasn't one of these front page stories; rather, it was an article relegated to page nine, entitled 'Cipher Expert Dares Zodiac To 'Tell' Name', the story described "a challenge perhaps unique in the annals of American crime...." Read more.