From 1969 to 1974 the serial killer known as the Zodiac stalked the San Francisco area killing at least 5 people on his rampage Betty Lou Jensen, David Arthur Faraday, Darlene Elizabeth Ferrin, Cecelia Ann Shepard, and Paul Lee Stine as well as harming Michael Renault Mageau and Bryan Calvin Hartnell. It seems that he preferred to attack young couples and survivors said he would wear a terrifying all black disguise with a black sack over his face. While any serial killer is awful the thing that set the Zodiac apart from most other serial killers is the cryptic coded messages he sent to police and the media.
On August 1st 1969 he sent his first letter to 3 area newspapers that revealed details only the killer would know, this established that the person really was the killer and that more murders would happen if people didn’t comply with him. It also contained the first of 3 parts to a coded message the 408 cipher. Six days later another letter called the Dear Editor Letter arrived at the desk of the San Francisco Examiner it gave even more details to the crimes and was the first time the killer referred to him self by the notorious Zodiac. It also told authorities that if they cracked all his codes they would learn his real name. The next day Donald Harding a school teacher and his wife Bettye Harding both amateur cryptographers solved the first message. It reveled only that the killer enjoyed his killing and that he intended to continue killing until he was stopped.
For over a month there was nothing until on October 14th a letter was sent to The Chronicle with a piece of Paul Stine’s shirt a local cabby that was murdered recently and It said that the Zodiac wanted to attack a school bus. On November 8th he sent a post card and the famously unbreakable 340 cipher the second part of the code. The next day arrived his longest message yet a 7 page almost manifesto detailing all of his crimes. Then on April 20th he sent the 3rd piece of the cipher simply a sentence saying “My name is -” and then a set of 13 characters. Over the summer of 1970 he would continue to send stuff to various newspapers and the police never letting them forget he was out there. He one time claimed to have built a bomb to attack a school bus like he mentioned in the dear editor letter and continuing to give strange demands. His final message was sent January 29th 1974 after 3 years of silence it included lines from a play called the Mikado that was in a previous letter and talked about the film The Exorcist. After that the Zodiac never officially sent any other messages.
So why is that the 340 named for the number of characters and the My Names Is cipher so hard to solve? For one they are are all pretty short messages and this makes it hard to use a process called frequency analysis to look for patterns in the number of letters used in the letters. Any rare word or combination of words would throw off the numbers. Also the messages are not just a code where letters are rearranged they are a cipher meaning that each letter corresponds to a made up symbol. This means that letters could share a symbol or symbol could match no letter at all. To make matters even worse many of the words in the earlier solved 408 had been misspelled leading some to wonder if the killer did it it on purpose to confuse code breakers or had some type of dyslexia.
Many skilled code breakers have tried to crack the Zodiac cipher with no luck but in 2017 a super computer names Carmel developed by Kevin Knight took a crack. Carmel works by comparing trillions of patterns in human languages and applying them all to a given source material. As of now even Carmel is stumped probably due the previously mentioned misspellings and shortness of the text but it has given a few very promising hints. Several people have also claimed to solve the ciphers through various methods but the FBI, various cryptographic associations, and other investigators have never been really convinced by any of the results but they are still always looking for new evidence even after 48 years. Many have even wondered if there is really any meaning behind other 2 messages and speculate it was all just a sick joke. If the Zodiac’s cipher’s have stumped even a super computer then it may never be solved and worse the at least 7 victims might never find justice. It’s disheartening the killer was never caught but we can take some comfort in the fact that even after 48 years tons of people from code breaking experts to amateur sleuths are still hard at work on the case and names of victims unlike the killers have never been forgotten .