Netflix's 'This is the Zodiac Speaking' tells the story of the hunt for a serial killer. Here's what happened to murder suspect Arthur Leigh Allen.

• "This is the Zodiac Speaking" details the hunt for a serial killer in the 1970s.
• The Netflix docuseries explains that police suspected Arthur Leigh Allen was the Zodiac Killer.
• Allen wasn't convicted and maintained his innocence until he died.

"This is the Zodiac Speaking" examines five murders that took place in San Francisco between 1968 and 1969, which were thought to be committed by the same man.

He was dubbed the Zodiac Killer because he sent letters to the police and various newspapers in San Francisco referring to himself as "the Zodiac." These writings contained clues about his identity and mysterious cryptograms, leading to much speculation over who the culprit was and his motive.

He claimed in some notes that he had murdered 37 people, but that was never confirmed. Police suspected a man called Arthur Leigh Allen, a convicted sex offender, may have been the Zodiac Killer.

True crime has become a core part of Netflix's business, and the show follows hits including "Lover, Stalker, Killer" and "The Asunta Case."

Here's what happened to Allen.

DNA evidence didn't point toward Allen.

As detailed in the series, the police considered Allen a suspect in 1971 after his friend, Don Cheney, told the authorities that he made remarks about "'shooting tires on the school bus and picking the little darlings off as they come bouncing out of the bus.'"

It's similar to a line in one of the Zodiac's letters, which threatened to "shoot out the front tire and then pick off the kiddies as they come bouncing out."

The San Francisco Police Department found hunting knives and a freezer filled with dead animals in Allen's trailer. The documentary included audio from police inspector David Toschi, in which he said: "We came away a little depressed. I thought we would find more."

In 1974, Allen was arrested and charged with child molestation. He pleaded guilty and spent three years in Atascadero State Hospital, California, and was released on a suspended sentence in 1977.

In 2002, police inspector Kelly Carroll told the San Francisco Chronicle that DNA evidence didn't point toward Allen.

"Arthur Leigh Allen does not match the partial DNA fingerprint developed from bona fide Zodiac letters," he said.

"It really comes down to DNA. Without it, you have nothing," Vallejo police detective Terry Poyser told The Sacramento Bee in 2019. "It's a 50-years-old case."

Arthur Leigh Allen maintained his innocence and died in 1992.

Allen died on August 26, 1992, at his home in Vallejo, California, of arteriosclerotic disease.

In a 1991 interview with The Examiner Allen maintained his innocence, and claimed to have received a document from the Department of Justice that said he was not the Zodiac Killer.

However, he couldn't produce the document and stated that police had seized it when searching his property.

"This damned thing has been haunting me for 22 years," Allen said "If I was prone to suicide, I'd already have done it... The only thing in my favor is, I've never killed anyone."

He added: "No way in hell I could go out and kill innocent teenie-boppers, no way. But with (the police), I'm guilty until I'm proven innocent, and I figure the case will be around until I die."