SAN FRANCISCO (NEXSTAR) – A team of investigators calling themselves The Case Breakers say they know the identity of the Zodiac Killer, but law enforcement is refuting their claim.

The serial murderer killed five people in Northern California in 1968 and 1969, taunting investigators with with a series of cryptic notes.

The Case Breakers, a group of 40-plus members led by retired FBI agents have varied backgrounds in law enforcement, according to their site, and work to solve some of the country’s most notorious cold cases. The Case Breakers have previously attempted to tackle the D.B. Cooper case and the death of Jimmy Hoffa, according to FOX.

The self-described task force identified an Air Force veteran who lived near Northern California’s Sierra Nevada as the Zodiac Killer in a story first reported by FOX News on Wednesday. The man they named died in 2018. (Nexstar is opting not to name the man in The Code Breakers’ report in light of refutation from law enforcement).

The group said they also believe the Air Force veteran is responsible for killing a sixth victim, 18-year-old Cheri Jo Bates on Oct. 31, 1966 in Riverside, California and stated that detectives recovered “hairs, skin and blood” from under her fingernails. They are calling on the department to test the alleged evidence – which they say is stored in the Northern California city of Vallejo – against that of the person they identified in the case.

Riverside Police Officer Ryan Railsback told Nexstar that his department is unaware of any such physical evidence and questioned where the cold case team was getting its information. Railsback said that Riverside investigators have worked closely with the labs and law enforcement teams to investigate any possible link.

“If the Cheri Jo Bates case was actually related to the Zodiac Killer, we wouldn’t be holding that back, especially 55 years later,” Railsback said. “Unequivocally, we are saying that the Cheri Jo Bates case and the Zodiac Killer case are not related.”

Railsback said that the Riverside Police Department’s Cold Case Unit did receive a handwritten letter in 1967 that initially led investigators to believe the Zodiac Killer might have been behind her murder. The department received a second letter, this time typed, apologizing for the letter and saying it was written as a “sick joke.”

In 2020, the Riverside Cold Case Unit and the FBI Los Angeles Investigative Genealogy Team used DNA evidence from the stamp on the 2016 letter to track down the author and confirm that he wrote both letters. The letter writer, who was a teenager in 1967, wasn’t involved in the murder of Bates, investigators determined.

There is a standing $50,000 reward for information leading to Cheri Jo Bates’ killer set to expire Jan. 31, 2022, according to Riverside police, who said that a lawyer working with the The Case Breakers had inquired about in September.

The Riverside Police Dept. is asking anyone with tips on the Zodiac Killer to contact the FBI instead.

A Vallejo police spokesperson said the department could neither confirm nor deny Wednesday’s report from The Case Breakers, and added that they would announce any major developments.

San Francisco police and the FBI also cast doubt on the Case Breakers’ announcement to the San Francisco Chronicle. “The Zodiac killer case remains open. We have no new information to share at the moment,” the FBI told the newspaper Wednesday.

Several conflicting theories have emerged in the decade since the Zodiac crimes. The San Francisco Chronicle – which received coded ciphers at the time of the killings – says it has received piles of letters “naming hundreds of suspects” over the years.

According to the Fox News report, the team of cold case specialists say new forensic evidence, decoded notes and photos from the suspect’s own darkroom led them to the identity of the Zodiac Killer.

In one case, The Case Breakers removed the letters of the Air Force veteran’s full name and discovered a message in the remaining text.

“So you’ve got to know [the suspect’s] full name in order to decipher these anagrams,” said Jen Bucholtz, a former Army counterintelligence agent. “I just don’t think there’s any other way anybody would have figured it out.”

In December 2020, a cryptographer and two software engineers cracked a cipher sent to the San Francisco Chronicle more than 50 years ago, the FBI confirmed.

The Zodiac would write notes, often threatening to kill, in a cryptogram composed of a bizarre series of letters and symbols. The killer signed the letters with a circle divided by a cross. Subsequent letters began, ″This is the Zodiac speaking.″

His last authenticated letter to the San Francisco Chronicle arrived Jan. 30, 1974.

Police say at least five people are believed to have been murdered by the Zodiac, although the killer claimed at least 37 victims since 1966 in his letters.

The killing spree has since been the subject of numerous theories, podcasts and even major motion pictures.