The Zodiac is the pseudonym of an unidentified serial killer who murdered at least five people in the San Francisco Bay Area between December 1968 and October 1969. The Zodiac attacked three couples and a cab driver in Benicia, Vallejo, unincorporated Napa County, and the city of San Francisco. The Zodiac's murders, cryptograms, and letters to newspapers have made the case one of the most famous unsolved cases in American history.
Despite several theories about the Zodiac's true identity, the only suspect police named was Arthur Leigh Allen, a former elementary school teacher and convicted sex offender who died in 1992. In 2004, the San Francisco Police Department marked the case "inactive," but subsequently re-opened the case in 2006.
From 1969 to 1974, the Zodiac sent over twenty letters to newspapers, police, Chronicle writer Paul Avery, and attorney Melvin Belli.
Police and investigators concur The Zodiac attacked seven people on four occasions in California:
- Betty Lou Jensen (16) and David Arthur Faraday (17)
- Michael Renault Mageau (19) and Darlene Elizabeth Ferrin (22)
- Bryan Calvin Hartnell (20) and Cecelia Ann Shepard (22)
- Paul Stine
The First Murders and Initial Communications
The first murders retroactively attributed to the Zodiac were the shootings of high school students Betty Lou Jensen (16) and David Arthur Faraday (17) on December 20, 1968. Faraday picked up Jensen, and the couple visited one of Jensen's friends. Police determined that their assailant parked his vehicle about ten feet alongside the passenger side of Faraday's car. He fired several shots at Faraday's car as he walked around to the driver's side.
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The couple scrambled to get out through the passenger door; Jensen succeeded. As Faraday was exiting, the killer shot him in the head with a .22-caliber pistol. The assailant chased Jensen as she fled, firing six shots at her back. Jensen was dead. Faraday was still breathing but died at the hospital. There were no witnesses and no usable tire or foot prints. The only motive the police could deduce was a "madman" wanting to kill.
Darlene Ferrin (22) and Michael Mageau (19) were shot shortly after midnight on July 4, 1969. On July 4, they went on a date despite the fact that Ferrin was married. Immediately after leaving Mageau's house, the couple noticed they were being followed by a man in a light-colored car. Ferrin drove out of Vallejo in the direction of Lake Herman Road. Shortly before midnight, she turned her car into an empty parking lot at Blue Rock Springs Park. Another vehicle parked about 80 feet to their left. The driver turned his headlights off and sat motionless. Five minutes later, the stranger returned, parked a few feet next to Mageau's side of the car and got out. He shone a flashlight into Ferrin's car as he approached. Without speaking, the stranger fired a 9mm pistol into the car.
One bullet hit Mageau in the right arm, and the other hit Ferrin in the neck. Mageau tried to leave the car, but his door handle was missing or removed. The assailant returned to his car, opened the door, and shot him and Ferrin two more times each. The killer hurried into his car and drove off. Three teenagers drove into the parking lot, saw the wounded couple, and got help. Twenty minutes later, Ferrin was pronounced dead at the hospital. Mageau survived and described the attacker as a heavyset white man, around 5'8" tall.
On August 1, 1969, the Vallejo Times, San Francisco Chronicle and San Francisco Examiner all received letters written by someone taking credit for the attacks in Vallejo. Enclosed in all three letters was a different cryptogram. They combined to form a 408-symbol cipher (Z408). The writer claimed, "In this cipher is my idenity [sic]." He demanded the codes be printed on each newspaper's front page. If they were not, he threatened to "cruise 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 Chronicle published its third of the cryptogram inside the August 2 edition. In the accompanying article, Vallejo Police Chief Jack E. Stiltz said, "We're not satisfied that the letter was written by the murderer". In this second letter to the media, the killer wrote at much greater length. He happily obliged Chief Stiltz's request for more information about both murders. He provided minute details about how he shot Michael Mageau. Regarding the Lake Herman Road attack, he revealed that he had taped a flashlight to his gun in order to aim easily in the dark. The August 4 letter also referred investigators back to the Z408 cipher.
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The Z408 Cipher and Its Decryption
Part 1 of Z408 cipher and its decryption by Donald and Bettye Harden. On August 5, it was cracked by Donald and Bettye Harden, a couple in Salinas. The message was rife with misspellings and referred to Richard Connell's 1924 short story "The Most Dangerous Game". The Zodiac explained killing was a way of collecting slaves for his afterlife.
The decoded message did not reveal the Zodiac's identity. VPD asked a psychiatrist at the California Medical Facility in Vacaville to analyze the Zodiac's message. The doctor concluded the writer felt omnipotent based on his fantasy about collecting spiritual slaves. The analysis described the Zodiac as "someone you would expect to be brooding and isolated".
Lake Berryessa Attack
On September 27, 1969, Pacific Union College students Bryan Hartnell (20) and Cecelia Shepard (22) were picnicking at Lake Berryessa on a small island connected by a sand spit to Twin Oak Ridge. Sometime later, Shepard noticed a man watching them. When he emerged from behind a tree, he put on a black executioner's hood with clip-on sunglasses. He wore a bib with a white 3x3" symbol on it. He brandished a gun, which Hartnell believed was a .45. Before tying up Shepard, the Zodiac made Shepard bind Hartnell with precut lengths of plastic clothesline. He tightened Hartnell's bonds because Shepard's knots were too loose. Hartnell still believed they were being robbed when the Zodiac drew a knife and stabbed them.
The Zodiac hiked 500 yards to Knoxville Road, leaving several footprints for investigators to study. After hearing the victims' screams, a fisherman and his son sought help. Hartnell untied Shepard's ropes with his teeth, and she freed him. Two park rangers arrived and tended to the stricken couple until the ambulance arrived. Shepard was conscious and gave a detailed description of their attacker. She and Hartnell were taken to a hospital in Napa. Shepard lapsed into a coma during transport; she never regained consciousness and died two days later.
Earlier that day, a suspicious man had been seen around Lake Berryessa by several people. A dentist and his son saw a heavyset man looking at them from a distance before he hurried off. Since they had potentially seen the Zodiac without his hood, the women worked with Napa Valley Register photographer Robert McKenzie to create a composite sketch using an Identi-Kit facial compositing device.
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The Zodiac drove 27 miles from the crime scene to a car wash in downtown Napa. He told the dispatcher he wished to "report a murder - no, a double murder" and confessed to the crime. He did not hang up the phone. KVON radio reporter Pat Stanley found the phone off the hook a few minutes later. The payphone was located a few blocks from the sheriff's office.
The Murder of Paul Stine
The last confirmed Zodiac murder took place two weeks after the Lake Berryessa attacks. On October 11 in downtown San Francisco, the Zodiac hailed a cab which was driven by a doctoral student named Paul Stine. When the taxi arrived at Washington and Maple streets, the killer asked to be driven another block. Three teenagers witnessed the crime from a house directly across the street from Stine's cab. The Zodiac's face was clearly visible by streetlight. The teenagers watched as the Zodiac wiped down the vehicle and rifled through Stine's clothes. He left behind two partial fingerprints from his right hand.
While the Zodiac was tending to the cab, the kids called the San Francisco Police Department (SFPD). They described the criminal as a "husky" white man in a "dark or black jacket". Just two minutes after the call to SFPD, two nearby patrol officers responded to the radio dispatch. They encountered a white man in dark clothes walking north towards the Presidio army base. They pulled alongside the man and asked if he had seen anything suspicious. The man confirmed he had seen someone waving a gun and heading east. The officers hurried away. The Zodiac later claimed he was the witness that spoke to the two officers.
When police arrived at the scene, Stine was declared dead. SFPD canvassed the area, including the Presidio. Police assumed the murder was a result of the robbery. The teenage witnesses helped a police artist make a composite sketch of the man they saw at Stine's cab. The two patrol officers who questioned the witness near the scene realized it may have been the Zodiac. SFPD detectives Bill Armstrong and Dave Toschi were assigned to the case.
Toschi ended up working on the case by himself and filled eight filing cabinets with potential suspects. In 1976 he told the Associated Press that Zodiac's letters were an "ego game". He believed the killer lived in the San Francisco Bay Area, "He's a weekend killer. Why can't he get away Monday through Thursday? Does his job keep him close to home?
After working on the Zodiac case for seven years, Toschi started writing anonymous letters praising his own investigative work to Chronicle columnist Armistead Maupin. Two years later in 1978, Toschi was removed from the case and demoted to pawn shop detail. He expressed regret for the hoax.
The Zodiac's Letters and Ciphers
The Zodiac's communications were marked by taunting letters and complex ciphers sent to the press. These ciphers purportedly contained information that would lead to his arrest, but decades passed without law enforcement catching the killer.
Here are some of the communications sent by the Zodiac Killer:
- July 31st 1969: San Francisco Chronicle, San Francisco Examiner, and Vallejo Times. One-third of "Z408 cryptogram" enclosed with each letter.
- August 4th 1969: Examiner.
- October 13th 1969: Chronicle. Swatch of Paul Stine's shirt.
- November 8th 1969: Chronicle. "Z340 cryptogram." The "Dripping Pen" card.
- November 9th 1969: Chronicle. Bomb diagram.
- December 20th 1969: Melvin Belli. Swatch of Stine's shirt.
- April 20th 1970: Chronicle.
- April 28th 1970: Chronicle. Greeting card.
- June 26th 1970: Chronicle.
- July 24th 1970: Chronicle.
- July 26th 1970: Chronicle.
- October 5th 1970: Chronicle. Thirteen-hole punch card.
- October 27th 1970: Paul Avery at Chronicle. Halloween card.
- March 13th 1971: Los Angeles Times.
- January 29th 1974: Chronicle.
The Z340 Cipher
The second cipher, known as “the 340” due to the number of characters in it, would prove a much more difficult challenge. It came with a letter for the Chronicle, reading in part:
PS could you print this new cipher in your frunt page? I get aufully lonely when I am ignored, so lonely I could do my Thing !!!!!!
The paper’s editors, along with local law enforcement officials, had no reason to doubt the Zodiac’s most recent threat. They published the 340 the next day, hoping it might bring them one step closer to the serial killer’s identity, or lead them to his next victims.
But the 340 stumped both amateur and professional cryptographers alike-not just in the weeks following its publication, but for decades. The NSA couldn’t crack it. Neither could the Naval Intelligence Office or the FBI. For more than fifty years, the cipher remained an unsolvable enigma, one that grew to almost mythic proportions among codebreakers and cryptography sleuths. Some speculated that the cipher would never be solved-that it was too sophisticated, too challenging for even contemporary cryptographers.
Decryption of the Z340 Cipher
In December 2020, the FBI announced a breakthrough: The 340 cipher had been solved. Not by its crack Cryptanalysis and Racketeering Records Unit, but instead by three computer wonks who’d found one another on an obscure online true-crime discussion board and started collaborating during the COVID-19 pandemic. The trio, who had no background in cryptology and no professional codebreaking experience, did what the world’s most powerful intelligence organizations could not. On top of the solution’s haunting opacity, the intricacies of the cipher itself brought fresh layers of insight that, forensic experts say, might help authorities eventually, finally, catch up to the killer.
The Zodiac’s first cipher, included in the July 31 letter, had been solved within a week by an amateur husband-and-wife team-but it had only revealed more of the killer’s raving.
Around the time when the Zodiac Killer sent the Z340 cipher, an imposter dialed The Jim Dunbar Show. The imposter claimed he was the killer, and he was scared of the “gas chamber”. They figured that a “gas chamber” would appear in this text. And it did. The cipher highlighted that the “gas chamber” did not scare the Zodiac Killer. It is because the killer believed that the “gas chamber” would send him to “paradice”, where he has already sent some of his “slaves”. In fact, he killed people who would become his slaves in “paradice”.
Notably, another obstacle in the deciphering of the ciphers was misspellings. For instance, the spelling of paradise. It was probably done on purpose. But then, who knows?
In 2020, Melbourne, Australia, had a 112-day lockdown of the entire city to help stop the spread of COVID-19. The wearing of masks was mandatory and we were limited to one hour a day of outside activity. Otherwise, we were stuck in our homes. I was inspired by a YouTube video by David Oranchak, which looked at the Zodiac Killer’s 340-character cipher (Z340), which is pictured below. In his presentation, David explored the idea that the cipher is both a homophonic substitution cipher and a transposition cipher.
Essentially all my work on the Z340 was done in Mathematica. I used the Spartan high-performance computing cluster at the University of Melbourne to eliminate candidate transpositions using zkdecrypto and David used AZdecrypt. Otherwise, all the statistical analysis of the Z340 and the creation and analysis of the millions of candidate transpositions was done using Mathematica. Sam Blake has a PhD in mathematics from Monash University in Australia and is a research fellow at the University of Melbourne. He’s been an avid Mathematica user since 2004 and worked for Wolfram Research for four years.
Here’s a table summarizing the key aspects of the solved Z340 cipher:
| Aspect | Description |
|---|---|
| Cipher Type | Homophonic substitution cipher and a transposition cipher |
| Decryption Tools | AZdecrypt, zkdecrypto, Mathematica |
| Key Techniques | Period-19 transposition, knight's move, cribbing |
| Decryption Team | David Oranchak, Sam Blake, Jarl Van Eycke |
The Unsolved Z13 Cipher
The Zodiac Z13 cipher has been the subject of much speculation and analysis. Let’s explore some of the proposed solutions:
- “No Name No Name”:One interpretation suggests that the Zodiac symbol represents “zero at North,” resulting in the phrase “No Name No Name” when read around the wheel using opposite sectors for substitutions. This solution remains consistent regardless of how many times you spin the wheel or in which direction.
- “KAYR”:Another amateur sleuth claimed to have cracked the Z13 cipher, resulting in the partial solution “KAYR.” This is close to the name “Lawrence Kaye,” a longtime suspect in the Zodiac murders.
- “I am Kane. I am a man. I am aka Zodiac.”:Yet another interpretation reveals the phrase “I am Kane. I am a man. I am aka Zodiac” when deciphered. This solution provides a more detailed message, but its authenticity remains uncertain.
Gemini: The Zodiac Z13 cipher is unfortunately very difficult to crack due to its short length. This makes it hard to apply common decryption methods that rely on frequent letter patterns.
The Zodiac's last letter was received by the San Francisco Chronicle in 1974. Two of the Zodiac's four cryptograms were decrypted in 1969 and 2020, and the other two remain unsolved.
The complexity and notoriety of the Zodiac's ciphers continue to captivate amateur sleuths and researchers alike, making them an enduring mystery in true crime history.