San Francisco Chronicle via AP This is a copy of a cryptogram sent to the San Francisco Chronicle, Nov. 11, 1969. by the Zodiac Killer. The Zodiac killer is blamed for at least five murders in 1968 and 1969 in the San Francisco Bay Area. He was never caught, though many, including Graysmith, believe he was Arthur Leigh Allen, a Vallejo man who who died in 1992.

He was one of the great — if that’s the word for it — serial killers in modern American history. Over several months in 1968 and 1969, the Zodiac Killer stabbed or shot five people in the Bay Area, then taunted authorities in some two dozen cryptic messages sent to the San Francisco Chronicle and other publications until 1974. Now, more than 40 years later, a former California Highway Patrol officer says he knows who the murderer was — and that he’s still alive.

In his new book The Zodiac Killer Cover Up, Lyndon Lafferty claims that the Zodiac killer is a 91-year-old alcoholic who lives in Solano, Calif. — where the murders began — and whom he will only identify with a pseudonym, George Russell Tucker.

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Lafferty, 79, says he encountered the man at a rest stop in Vallejo, Calif. in 1970, when the suspect parked close to Lafferty’s patrol car. “I looked into a quivering, snarling face like I was looking to the face of death,” Lafferty recalled in a profile in the Chronicle last year, noting the similarities the man bore to sketches of the Zodiac Killer. “It scared the hell out of me.” Lafferty collaborated in his research with six fellow detectives, including other law enforcement officers who investigated the Zodiac case at its height. They claim the man they call George Russell Tucker was known to be a regular at the Vallejo restaurant where one of the victims, Darlen Ferrin, worked; that a car resembling Tucker’s was seen around Ferrin’s house in the weeks before the killing; and that strange graffiti markings were discovered around his Cordelia, Calif., home. Lafferty also claims that Tucker’s real name was spelled out in one of the cryptograms the Zodiac Killer sent to the media.

“As God is my witness, my partners and I have always tried to share our material and our case with the proper authorities, but in the past 40 years the latter have ignored and stymied and stonewalled us again and again,” Lafferty writes.

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Lafferty maintains that power brokers of Solano County thwarted the case, including a judge that was having an affair with the suspect’s wife — an affair that may have prompted the murder spree in the first place. The San Francisco police formally closed the case in 2004.

In his 2011 Chronicle interview, Lafferty said he was prepared for his theory to be received with skepticism:

“Look, I know what most people think of Zodiac theories, and there have been so many over the years that if a person walked into the Vallejo Police Department right now and said he was the Zodiac, they’d tell him to get out. But I do feel that we gave a very credible case.”

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