Scott Peterson Breaks His Silence: ‘I Was an A-Hole’ to Laci—But 'I Didn’t Kill My Wife’ (Exclusive)

Sitting in the noisy dayroom of Mule Creek State Prison in Ione, Calif., as he speaks over a grainy video call, Scott Peterson looks more like a laidback surfer than a man convicted of the heinous 2002 murder of his wife Laci and their unborn son Conner.

His hair, which he sometimes wears in a ponytail, is long and tousled, his demeanor calm and friendly, as described in this week's People cover story.

But he turns serious as he discusses the terrible mistake he made when—a month before the murders—he began an extramarital affair with a Fresno, Calif., massage therapist named Amber Frey.

“It’s horrible,” he says. “I was a total a-hole to be having sex outside our marriage.”

In speaking out for the first time on camera since before his arrest 21 years ago, Scott isn’t just seeking to set the record straight on his affair.

In Face to Face with Scott Peterson, a new three-part docuseries premiering on Peacock on Aug. 20, the former Modesto, Calif., fertilizer salesperson—now serving a life sentence without the possibility of parole—is once again denying any involvement in the disappearance and death of Laci and the child she was carrying.

He is also appealing to the public to listen to his side of the story of what he calls the “so-called investigation” carried out by police and prosecutors who, he claims, ignored significant leads and relied solely on circumstantial evidence in their quest to convict him of double murder during his trial in 2004.

Says Scott: “I regret not testifying [at my trial], but if I have a chance to show people
what the truth is, and if they are willing to accept it, it would be the biggest thing that I can accomplish right now—because I didn’t kill my family.”

The Peacock doc also chronicles the appeal launched last January by the Los Angeles Innocence Project in an attempt to overturn Scott’s conviction by proving his innocence.

During his five-month-long murder trial that ended in November 2004, prosecutors described Scott as a man who regretted that he was soon to become a father and committed murder to get out of his marriage without having to pay spousal and child support.

“That is so offensive and so disgusting,” he says about the prosecution’s allegations. “I certainly regret cheating on Laci, absolutely. It was about a childish lack of self-esteem, selfish me traveling somewhere, lonely that night because I wasn’t at home. Someone makes you feel good because they want have sex with you.”

For more about Scott Peterson and the new documentary, subscribe now to PEOPLE or pick up this week's issue, on newsstands Friday.

One of Peterson’s staunchest supporters in the documentary is his sister-in-law Janey Peterson, who became a lawyer in part to fight for his freedom, She tells PEOPLE that Scott's affair and his dishonesty was "devastating and upsetting" to her and Scott's family.

“Scott lied about cheating and that was upsetting,” says Janey Peterson. “But he wasn’t charged with infidelity. He was charged with murder.”

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