It's been more than three decades since the puzzling case of the Zodiac Killer unfolded and now a former California Highway Patrol officer is unmasking in his new book who he believes the killer is.
In "The Zodiac Killer Cover-up, AKA The Silenced Badge," Lyndon Lafferty, 79, lays out 40 years of evidence to build an accusation that a 91-year-old recovering alcoholic and Fairfield, Calif., resident was the Zodiac Killer.
"This was a story that I inherited. I did not ask for it," Lafferty told ABC News. "I am the only person who can testify under oath that these things were absolutely true. My satisfaction is telling my story as it happened."
During the time of the murders, Lafferty claims he encountered the Zodiac Killer himself while on parole as a CHP officer in 1970. Since then, Lafferty has investigated the case along with six other law enforcement officers. In 2002, he began to compile his notes from the past 30 years and began writing his own story of the case.
"This has been our experience of over 30 years of very dedicated and consistent investigation," Lafferty said. "I have one chapter devoted to 156 circumstantial factors of evidence that related to the Zodiac case and our suspect."
The Zodiac killings, which occurred in the late 1960s in and around San Francisco, got their name from the suspect's use of zodiac symbols as his signature on letters with cryptic messages to local newspapers. While the killer claimed he took the lives of 37 people, authorities were only able to link the suspect to five murders.
Lafferty said the Zodiac killer's rage was driven by jealousy after he found his wife having an affair. As for why he's coming out with his story 40 years later, he said the case was ignored by several police agencies and repressed by a judge who Lafferty claims was having an affair with the suspect's wife.
"The police departments in general were acting under the authority of the Solona County Sheriff, so they were instructed you do not investigate this man until you have permission from the judge," Lafferty claims. "It's been very traumatic, and it's been frustrating beyond belief."
Lafferty's book isn't the first written on the Zodiac killings, and there was also a movie inspired by the unsolved mystery.
No one has ever been arrested in the case.