Cracking the Code: Who is the Zodiac Killer?

By: Andrea Cipriano, MAFP

“Dear Editor, This is the Zodiac speaking…”

Who is the Zodiac Killer?

The Zodiac Killer was a notorious serial killer active in Northern California in the late 1960s and early 1970s. He is believed to have killed at least five people, though he claimed to have killed as many as 37 people. 

Police sketch of the man suspected of being the “Zodiak Killer,” 1969.

The Zodiac’s usual method of killing was to target teenage couples and strike when they were in some secluded area. Most of his victims were at lover’s lanes and in a car. He would kill them by shooting with a pistol or stabbing them with a knife. 

He communicated with the media and law enforcement through a series of letters and ciphers. The letters began with the words: “This is the Zodiac speaking” and contained various taunts alluding to his planned murders. The media ran with the frenzy, and his own name stuck. 

Only a few people have survived or witnessed the Zodiac Killer in action, but thankfully they’ve been able to provide a detailed physical description of what he looks like.

The killer has been described as being roughly 5’8” to 5’10” with curly brown hair styled in a crew cut. He had horn-rimmed glasses and was described as wearing dark clothing with distinctive shoes known as “Wing Walkers — military jump boots. Thankfully the boots left deep impressions at a few of the crime scenes, so investigators were able to cast the pattern.

They discovered the killer wore a size 10.5 shoe.

John Douglas, retired FBI Criminal Profiler, detailed in his book The Cases That Haunt Us that the Zodiac is an “attention-seeking, paranoid, self-conscious, narcissistic loner.” Douglas attributes his letters and communications with the media and law enforcement as evidence of his grandiose beliefs, noting that not many killers name themselves — or mail cryptic letters with symbols and secret messages.

The most infamous coded letter was the 340 Cipher.

What is the 340 Cipher?

In November of 1969, the Zodiac killer mailed the 340 Cipher, named after its 340 characters, to the San Francisco Chronicle. The cipher was a combination of letters, symbols, and numbers; all meant to disguise a hidden message meant to be decoded. The Zodiac claimed that the note contained his identity and that he would not be caught unless it was translated.

Cue the terrifying movie music.

Even though the 340 Cipher is infamous, it wasn’t his first correspondence with the media.

‘This is the Zodiac speaking’

On July 31st, 1969, the Zodiac sent his first nearly-identical 3-page letters to The Vallejo Times-Herald, The San Francisco Examiner, and The San Francisco Chronicle. In these letters, the writer not only gives himself the name Zodiac, but he also admits to killing a couple the previous year and offers facts about the crime that only the police would’ve known. He threatened that he would continue his murderous rampage if the letters were not printed on the front pages.

Page 1 of the Zodiac’s first letters mailed to the newspapers.

In October of the same year, one month before the 340 Cipher would be mailed, the Zodiac Killer sent a greeting card to The San Francisco Chronicle depicting a fountain pen being washed. It’s a haunting image with a sinister subtext.

The card itself reads, “Sorry I haven’t written, but I just washed my pen…and I can’t do a thing with it.”

He then added the words — spelling errors and all — “This is the Zodiac speaking. I though you would nead a good laugh before you hear the bad news. You won’t get the news for a while yet. 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 killer terrifyingly underlined the word “Thing” six times and added six exclamation points. Was he hinting at how many people he had already killed at the time? Some investigators believe so. 

Many of these letters and the ciphers that came along with them stumped investigators and codebreakers for decades. But, in December 2020, they finally had a break.

Cracking the Code

A team of codebreakers, led by David Oranchak, a web designer based in Virginia who was obsessed with the code for 14 years, did what experts couldn’t since the 70s — they solved the Zodiac 340 Cipher.

Oranchak made a series of YouTube videos about the cipher, which attracted others to his project. Building off Oranchak’s work, Australian-based mathematician Sam Blake calculated that there were 650,000 possible ways to read the code, and Jarl Van Eycke, whose day job is as a warehouse operator in Belgium, wrote the software that ultimately broke the cipher, according to a Vice report and interview with Oranchak.

The decrypted message was chilling. It says:

“I hope you are having lots of fun in trying to catch me
that wasnt 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
life will be an easy one in paradice death”

 

Translation of the cipher (decoded in December 2020) and corrected for most errors, excluding the distinctive spelling of “paradice”.

The Zodiac claimed that the note contained his identity, but no hidden name or identifying information could help investigators pin the crimes on one man. As the decades have gone by, the identity of the Zodiac Killer has never been definitively determined — but some believe they know the man behind the codes and deadly crimes.

Was Gary Francis Poste the Zodiac Killer?

In October 2021, a team of cold case experts known as the Case Breakers claimed to have identified Gary Francis Poste as the serial killer. However, their evidence has failed to convince police or other experts who have followed the case over several decades.

To that end, it’s worth exploring who Poste was and his background.

Researchers know that Poste lived in the town of Groveland, California — roughly 150 miles east of San Francisco. He was a former member of the US Air Force, and he died in August 2018 at 80 years old.

As a 20-year-old working at the Air Force radar station in Illinois, he was the passenger in a drunk-driving accident that killed his driving friend, according to the Evansville Courier & Press. Poste sustained injuries to his forehead from the accident leading to scarring, and had to have teeth pulled because of his injuries. Not long after the crash that took his friend’s life, Poste was shipped out to a radar station in Greenland, deemed one of the “loneliest and most isolated” bases in the world.

“That’s where we believe he lost it,” Thomas J. Colbert from the Case Breakers told the New York Post. “He came back to the US a different person.”

Poste’s own family members have accused him of being the serial killer, claiming he was abusive and violent … and have come with the police reports to prove it. Others who knew him, particularly his neighbors, had similar stories. One of Poste’s neighbors, Gwen, told Fox News that she recalls Poste teaching her how to fire a gun while witnessing his aggression firsthand.

Gwen says Poste’s wife often slept on their couch to escape his temper and aggression.

Did Gary Poste Run a Criminal Gang?

Colbert continued to tell the New York Post that there was a local group of about ten men who were called “The Posse.” He would accompany Poste deep into the Sierra Nevada mountains, where they would learn to “hike and kill animals for fun” and how to turn a pipe bomb into a bomb that would blow up houses.

At least one of “The Posse” members allegedly confronted Poste about potentially being the Zodiac.

Chris Avery, who went by “Wil” when originally talking to the media, confronted Poste about being the infamous killer after seeing sketches of the offender and recognizing the scar lines on his forehead. After making the accusation, Avery alleges that Poste came at him with a five-pound hammer.

“He just didn’t have a conscience,” Avery told the New York Post.

Cheri Jo Bates

Beyond connecting Poste to the Zodiac killer based on location, timeline, and propensity for violence, the Case Breakers also believe the Zodiac killer took the life of another woman who has never been formally linked to the infamous offender — but could be linked to Poste. 

They believe the 1966 murder of Cheri Jo Bates in Riverside, California, has Poste’s figurative fingerprints all over it.

Eighteen-year-old Bates was a college freshman when she was stabbed and slashed on the grounds of Riverside City College. Police determined that her killer disabled the ignition coil wire in her Volkswagen Beetle as a method to lure her out of her car after studying in the college library.

Police discovered a broken, paint-splattered watch at the crime scene that they later determined had been purchased at a military base.

It wasn’t Bates’ watch, so investigators believe it must belong to the killer.

Interestingly, Poste was a housepainter and spent time in the Air Force. At the time of Bates’ murder, Poste happen to have gone for a health check-up at the March Air Force Base hospital just 15 minutes away.

Experts say that checks “opportunity” for investigators — but the rest is conjecture without hard evidence. 

Police also found size ten footprints at the scene that match other Zodiac Killer footprints. The Case Breakers point out that Poste also wore a size ten shoe.

Other investigators have disputed these claims as speculation and coincidence.

Poste’s last years were grisly.

In 2016, he shoved his wife, 74, down the stairs of their home. He was found mentally incompetent to stand trial for the attack and ultimately died in custody in 2018 from sepsis, difficulty swallowing, and vascular dementia.

Today, the burning question of ‘Who is the Zodiac Killer?’ still smolders as the case is considered open and unsolved.