Was Gary Francis Poste the Zodiac Killer? We Can't Be Sure

A number of the Zodiac Killer's suspected victims were found at or near California beaches. code6d / Getty Images

Gary Francis Poste made headlines after his death as the suspected Zodiac Killer. But is there enough evidence to finally close this case?

Who Was Gary Francis Poste?

Gary Francis Poste (1937-2018) was an Air Force veteran and house painter who lived in Groveland, California. Poste was arrested in 2016 on domestic violence charges and died in 2018 at the age of 80.

In 2021, a civilian volunteer group called the Case Breakers announced they had identified Gary Francis Poste as the elusive Zodiac Killer "through a combination of evidence involving shell cartridges, photos, fingerprints, cryptic writings and DNA harvested from his old clothing and a blood relative."

Who Was the Zodiac Killer?

The Zodiac Killer is the alias of an infamous killer who terrorized the San Francisco Bay Area in the late 1960s. At least five murders are widely attributed to this serial killer:

High school students Betty Lou Jensen and David Faraday were both shot to death in December 1968 in Benicia, California.
Michael Renault Mageau and Darlene Elizabeth Ferrin were shot in July 1969 in Vallejo, California. Mageau survived the attack, but Ferrin did not.
Bryan Calvin Hartnell and Cecelia Ann Shepard were stabbed in September 1969 in Napa County, California. Shepard died as a result of her injuries, but Hartnell survived.
Paul Lee Stine was shot to death in San Francisco in October 1969.

Some people believe the 1966 murder of Cheri Jo Bates in Riverside, California, was also the work of the Zodiac Killer.

The Zodiac Killer's Cryptograms

The attention-seeking Zodiac Killer was able to generate a media frenzy by sending disturbing, cryptogram-containing letters to local newspapers, including the San Francisco Chronicle.

Two of the four cryptograms have been deciphered: The July 1969 "408 cipher" was decoded soon after its publication, while the November 1969 "340 cipher" was cracked in 2020 by a group of amateur code breakers and confirmed by the FBI.

As of April 2024, two of the Zodiac Killer's cryptograms remain unsolved. According to the New York Times, we may never know what they say for sure — because they are so short, it's difficult to definitively prove that a code-breaker has used the correct cipher.

At the time, the San Francisco FBI confirmed that the Zodiac Killer case "remains an ongoing investigation." Unfortunately, cracking the "340 cipher" did not provide any clues as to the Zodiac Killer's identity.

The unusual nature of the murders inspired films including "Dirty Harry" (1971) and "Zodiac" (2007).

Unofficial Zodiac Killer Suspects

Although law enforcement has not released the names of any official suspects in the Zodiac Killer case, amateur investigators have proposed several theories.

Arthur Leigh Allen: Allen was considered the most likely Zodiac suspect in the 1990s. The former Vallejo schoolteacher was institutionalized in 1975 on charges of child molestation.
Lawrence Kane: Kane allegedly stalked victim Darlene Ferrin before her death.
Ross Sullivan: Some believe Sullivan, a former library assistant at Riverside City College, was involved in Cheri Jo Bates's murder.
Earl Van Best Jr.: In his 2014 book "The Most Dangerous Animal," Gary Stewart claimed his birth father, Earl Van Best Jr., was the Zodiac Killer.

To date, none of the Zodiac Killer "suspects" have been proven guilty.

Evidence Suggesting Gary Francis Poste WAS the Zodiac Killer

The Case Breakers say they know Gary Francis Poste was the Zodiac Killer because of DNA evidence obtained from a hiking mat and blood relative as well as a tip from an FBI agent. Other "clues" include:

The Zodiac Killer was believed to have forehead scars; Poste had forehead scars as well.
The Zodiac Killer and Poste allegedly shared the same shoe size.
Poste lived near the areas where the murders occurred and owned firearms.

Evidence Suggesting Gary Francis Poste Was NOT the Zodiac Killer

Although outlets like the New York Post were quick to declare Gary Francis Poste the real Zodiac Killer after the Case Breakers' announcement in 2021, the FBI insists that their investigation of the Zodiac Killer remains open.

Many have pointed to the lack of hard evidence in the Case Breakers' claims.