Drew Peterson’s son said he believes his dad killed two of his former wives, Kathleen Savio and Stacy Peterson.

The revelation marks the first time Stephen Peterson has spoken out against his father’s alleged crimes in the years since Drew Peterson was first accused of murder. Convicted of killing his third wife Kathleen Savio, Drew Peterson is also suspected in the disappearance of his fourth wife Stacy Peterson.

Stephen Peterson, who now lives in his father’s Bolingbrook home and spends his days raising his half siblings who were left parent-less after the highly publicized trial, admitted in an interview on the Lifetime cable network show “Monster in My Family,” which aired last month, that his father likely killed both wives.

Asked if he believed his father killed Savio, Stephen Peterson said, “I’d say probably so.”

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In a recent interview with the Chicago Tribune, he revealed he also believes his father, a former Bolingbrook police sergeant, killed Stacy Peterson.

“Over time, you hear enough [from police]. They can’t all be full of s---,” he told the publication. “I don’t want to come out and say he did it… but I’m sure he did it.”

Peterson noted in both interviews that he still speaks to his father, who he says has never confessed to the crimes and has maintained his innocence.

“He was my hero for a long time,” he told “Monster in My Family” host Melissa Moore.

“He’s still my dad, I still love him but basically everything we knew, we were wrong. After seven, eight years, this is the first time I’m coming out and saying anything because now I have to bring myself at 36 years old… I’m not Drew Peterson’s son, you know, I’m Steve.”

For years following Savio’s 2004 death, authorities had ruled it an accident, saying it appeared Savio had slipped in a bathtub and drowned.

But when Stacy Peterson disappeared in 2007 at 23 years old, authorities reopened the investigation into the death of Savio.

Drew Peterson was ultimately found guilty and sentenced to 38 years in prison for Savio’s death. He remains a suspect in Stacy Peterson’s disappearance, though he has never been charged in the case.

During his time in jail, Peterson was also charged in a murder-for-hire case after prosecutors claimed he tried to have the prosecutor who put him behind bars killed. In that trial, he was sentenced to another 40 years in prison.

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In the years since Stacy Peterson’s disappearance, Stephen Peterson has lost his job at a suburban police department, accused of obstructing the investigation into his father by hiding guns, and he has also lost his marriage.

Last summer, Drew Peterson’s pension payments, which Stephen had been using to support their family, stopped. A day later, he reportedly said he received a call from Lifetime offering him $10,000 to appear on the show, a request he had previously declined.

He told the Tribune, “The time was right.” But Stacy Peterson’s sister, Cassandra Cales, told the publication she believed he went on the show because “he wants people to feel sorry for him.”

Stephen Peterson said when he first learned that Savio had died, he never questioned the idea that her death was accidental. But in the years since his father’s conviction, his belief has changed.

“After enough loss you kind of start to think, 'OK maybe he’s not the hero you thought he was,'” he said on the show.

The show featured commentary from relatives of both Stacy Peterson and Savio as well as a pastor who acted as a marriage counselor for Drew Peterson and a divorce lawyer for both Stacy and Savio.

In it, Stephen Peterson recalls violent arguments between his father and Savio.

“The entire house was destroyed, the cops showed up and, you know, it was his town so you know nothing was going to happen,” he recalled.

It was an anger both Stephen Peterson and relatives of Savio said they saw in Drew Peterson repeatedly.

Susan Doman, Savio’s sister who has been vocal about her sister’s murder, recalled a conversation with Savio where she said, “Drew said he’s going to kill me and it’s going to look like an accident and no one’s going to know.”

The Lifetime show featured a reunion between Doman and Stephen Peterson, who had not spoken to each other since Savio’s funeral.

“We decided this is not going to define us,” Stephen Peterson said.