WATERTOWN — The man a volunteer group of cold case investigators claims is the notorious Zodiac Killer has roots in the North Country.

Case Breakers, which includes former FBI agents, law enforcement officials and journalists, issued a statement Wednesday claiming now-deceased U.S. Air Force veteran Gary F. Poste, a 1956 graduate of Port Leyden Central School, was the person responsible for serial murders in the San Francisco area in the late 1960s.

The killer made national news by taunting investigators with cryptic letters sent to newspapers, threatening to continue killing if his letters were not published. In all, the Zodiac Killer claimed to have committed 37 murders, but has never been identified and is officially tied to six murders.

Case Breakers has previously named Poste as the killer, but claimed Wednesday that the group’s founder, Thomas J. Colbert, “found DNA on a 30-year hiking mat once owned” by Poste and that his organization “found the ancestral town of the now-dead Poste, where DNA from a blood relative was offered by a confidential informant.”

The statement claims that days later, “good profiles” from Poste’s relative and DNA from the mat were compared by forensic experts from five colleges and that “strong similarities” were found. While that would likely only demonstrate that the mat indeed belonged to Poste and that he is related to the second contributor of DNA, Case Breakers suggest federal investigators have not properly employed a national DNA databank that the group believes could connect Poste to the Zodiac killings.

Poste, who died in 2018, was raised in Lyons Falls, Lewis County. His mother, Elva, who died in 2009, was born in Pierrepont, St. Lawrence County, while his father, who died in 1992, was born in Parishville. The couple moved to Lyons Falls in 1945 when Poste was a youth.

As a junior in high school, Poste played on Port Leyden’s varsity basketball team that finished second in its division in the Lewneida league with a seven-win, five-loss season.

According to a Jan. 10, 1959, Times article, he joined the Air Force in November 1956. In early January 1959, when he was a 21-year-old airman, he was a passenger in a car driven by fellow airman, Robert A. McManus, 20, of Brooklyn.

The Times’ article says that the car smashed into the wall of an underpass of the Chicago & Eastern Illinois railroad southeast of Clinton, Indiana. McManus was killed in the crash, and Poste suffered a fractured leg, fractured jaw and loosened teeth. He was not expected to return to duty before the summer.

Times records also show Poste visited his parents in Lyons Falls in May 1969. According to a timeline of confirmed Zodiac Killer murders compiled by the History Channel, three of the killings would occur in the ensuing months, one each in July, September and October 1969.

Colbert, of Case Breakers, claims that since 2016, the FBI has “secretly listed” Poste, who lived for decades in Groveland, California, as a suspect in the Zodiac killings, citing a “senior FBI agent” who has acted as a “whistleblower” for the group for 18 months. The whistleblower, who appears to be a former agent, has allegedly told the group that the FBI has “partial DNA” of Poste “safely secured” at its lab in Quantico, Virginia.

The group claims that the FBI is not pursuing leads in the case. The FBI has repeatedly stated that its investigation into the Zodiac Killer is open and unsolved, the New York Post reported Thursday.

Colbert said Thursday that his organization’s involvement with the Zodiac Killer case and ultimately Poste came about at the request of four people in Groveland who are anxious to see the case solved after several decades.

“It is causing pain and suffering,” he said of the lack of resolution. “These families are just desperate.”

He said two production companies have expressed interest in making documentaries about the Case Breakers investigation.

Colbert has been investigating cold cases since 2011. He and his wife Dawna now oversee a task force of 40 investigators, led by former FBI agents and U.S. marshals.

Based in Sherman Oaks, California, Colbert said Thursday that it is his goal to have a network of investigators nationwide to help solve the thousands of unsolved murders annually in the country.