Charles Manson says he killed more people in newly released prison audio from "Making Manson"

The late, deadly American cult leader Charles Manson may have had more victims than previously thought, according to an upcoming documentary.

In a newly released audio from the docuseries "Making Manson," coming to Peacock later this month, the convicted murderer alleged he committed previously unknown killings south of the border. In a teaser clip, the musician-murderer is heard revealing details about his past to an undisclosed person from prison.

Directed by Billie Mintz, the docuseries includes 20 years' worth of "never-before-aired conversations" between those closest to the case including Manson himself, "who talks openly about his part in the infamous crimes, as well as his upbringing, criminal youth, and his true feelings about 'The Family,'" according to Peacock.

Manson died on Nov. 19, 2017, while serving multiple life sentences at California's Corcoran State Prison. He had struggled with gastrointestinal problems in his later years before his death at age 83.

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Manson: 'I left some dead people on the beach'

At the start of the teaser, Manson's former cellmate Phil Kaufman recalls the infamous cult leader squashing anything that got in his way "with velvet gloves."

"Charlie was very good at being evil and not showing it," Kaufman says in the clip.

The shot pans to a short interview with Gregg Jakobson, a Manson associate, who said he did not know about the cult leader's criminal past when he first met him.

"See, there’s a whole part of my life that nobody knows about," Manson is heard saying in the promo "I lived in Mexico for a while. I went to Acapulco, stole some cars."

Manson goes on to say he was involved in additional killings.

"I just got involved in stuff over my head, man. Got involved in a couple killings. I left my .357 magnum in Mexico City and I left some dead people on the beach."

Who are Charles Manson's victims?

Recognized during his prison years for the swastika sloppily carved onto his forehead, Manson ordered a legion of cult followers to carry out horrific attacks in and around upscale Los Angeles in the late 1960s. Manson did not participate in the killings directly but did orchestrate and direct them.

Manson and his followers are known to have killed nine people at four locations in July and August 1969.

One of the most famous victims was director Roman Polanski's heavily pregnant wife, actress Sharon Tate, who was brutally murdered in her Los Angeles home along with her hairstylist Jay Sebring, Folger's Coffee heiress Abigail Folger, and friends Wojciech Frykowski and Steven Parent. Police eventually traced the slayings to Manson's followers who used the victims' blood to write messages on the walls of Tate's home.

Other victims included grocery store owner Leno LaBianca and his wife Rosemary LaBianca in what prosecutors say was an attempt by Manson to start a race war.

Vincent Bugliosi prosecuted the Manson case and later wrote a bestselling book, "Helter Skelter," about the killings.

Manson follower Patricia Krenwinkel was convicted of killing Tate and helping to kill the LiBiancas.

Krenwinkel, who wrote “Helter Skelter” on a wall using the blood of one of the victims, remains incarcerated at age 76 at the California Institution for Women.

Online records show she has a parole hearing set in May. In 2017, Gov. Gavin Newsom denied her parole. Previously she had been denied being set free 14 times.

The governor also previously rejected parole recommendations for other followers of Manson. Another Manson follower, Susan Atkins, died of cancer in prison in 2009.

Watch the "Making Manson" promo

How to watch "Making Manson"

"Making Manson" premieres on Peacock on Tuesday, Nov. 19.

Natalie Neysa Alund is a senior reporter for USA TODAY. Reach her at [email protected] and follow her on X @nataliealund.

This article originally appeared on USA TODAY: "Making Manson": Charles Manson says he killed more people in prison audio