Netflix have released a new documentary on the most famously unsolved serial killer case in history: the Zodiac Killer.
The self-named serial killer is linked to five separate murders from the late 1960s, and has claimed to have killed as many as 37 people.
The case in part became so famous due to the fact the killer sent several letters mocking the police throughout their pursuit of him.
A cypher sent by the Zodiac Killer (Bettmann via Getty Images)
In 1969, the killer sent letters to three different local newspapers, which included now-famous cyphers.
The cyphers have since been solved, although they took years to crack.
Among their most infamous threats, the Zodiac Killer threatened to blow up a school bus full of children.
While no one suspect has ever been 100 percent determined, there is only one man that police have ever identified as a suspect.
This man, named Arthur Leigh Allen, is the focus of the new Netflix documentary, which includes interviews with childhood friends of the man.
Arthur Leigh Allen (central) with the Seawater family (Netflix)
Leigh Allen died in August 1992 and has never been officially confirmed to be the killer.
Several books have presented him as the most obvious suspect and, while never settling on whether he did it or not, the 2007 David Fincher film Zodiac presented him as the most likely killer.
In the new documentary though, childhood friends of Leigh Allen claim he confessed to the murders.
The doc, called This is the Zodiac Speaking, focused on the late Leigh Allen, a local schoolteacher and member of the US Navy.
He was also a convicted sex offender, and was discharged from the Navy and sacked from his job as a schoolteacher after allegations of sexual misconduct.
He was arrested in 1974 for molesting a 12-year-old-boy, and served two years in prison.
The new documentary interviews people who claim to have known Allen when they were children.
The claims in the documentary, without delving too deep into spoilers, are wild. They range from people saying he told them he was the Zodiac Killer, to saying he drugged them as kids and may even have ‘brought them along’ to the killings.
Those interviewed are all members of the ‘Seawater’ family, and Leigh Allen bonded with their mother, Phyliss, after their father was institutionalised.
They said their mother never believed he could have been the killer, but that after her death, they found letters between Phyliss and the sex offender.
In one, read in part in the series, he said: “Every time someone mentioned police to me, I’d jump.
“Seeing a murder headline would turn my palms sweaty.
“The most dangerous thing is when I almost decided to confess.”
This is the Zodiac Speaking is streaming on Netflix now.