Drew Peterson's stepbrother says in his first network television interview that conversations with Peterson made him highly suspicious Peterson was planning on killing someone.
"He said, 'How much do you love me?,'" the stepbrother, Thomas Morphey, told ABC News' "Good Morning America." "I said, 'I do.' And he said, 'Enough to kill for me?'"
Morphey, who has spoken to authorities about his experiences, remembers that conversation as having occurred the day before Peterson's fourth wife, Stacy Peterson, disappeared. He also told "GMA" of other conversations he recalled with his stepbrother that convinced him Peterson was up to no good.
Watch the full interview Monday morning on "Good Morning America."
Morphey told "GMA" that, at one point, his stepbrother mentioned a storage locker.
"I knew it wasn't, it wasn't good," Morphey said. "He was planning on killing somebody."
Morphey said his suspicions also were raised as he helped Peterson move a blue barrel, and he said Peterson told him, "This never happened."
The talk and other details he discussed with "GMA" led him to believe that he and Peterson were disposing of Stacy Peterson's body, Morphey said.
"You know, at that point, I was just, 'My God, what's goin' on?,'" Morphey added.
Drew Peterson's attorney, Joel Brodsky, has denied Morphey's account in published interviews, claiming Morphey has had a troubled past that included substance abuse. He suggested to ABC News that authorities do not believe Morphey's story.
"According to reports in the Joliet Harold, Thomas Morphey states that he feels both abandoned and betrayed by Illinois State Police and Will County prosecutors," Brodsky's statement said. "Obviously law enforcement, who reportedly interrogated Morphey for 40 hours and checked out his story, doesn't think much of Mr. Morphey's credibility, so why should anyone else?"
Morphey told ABC News he stands by his story.
Peterson Under Suspicion, Not Charged
However, in numerous public statements, he has repeatedly proclaimed his innocence.
Savio's 2004 death was ruled a homicide.
Stacy Peterson vanished in 2007 after reportedly telling her minister that Peterson confessed to killing Savio.
Drew Peterson has said Stacy left him for another man.
Peterson's prospective fifth wife, Christina Raines, reportedly called off their engagement after a January interview on ABC's "Nightline". Subsequent reports, however, suggest she still plans to marry Peterson this summer.
"The engagement is over because of your interviews," Peterson told ABC News' Martin Bashir earlier this winter.
The Marriages of Drew Peterson
Peterson, a father of four and former undercover police officer in the town of Bolingbrook, Ill., married his high school sweetheart at the age of 20. The marriage ended after he admitted to several affairs. Two years later, he married his second wife but again was said to be unfaithful.
During his third marriage, to Savio, police were called to the couple's house 18 times.
"I was a smart-ass," Peterson said. "She'd get mad at me for something. She'd be going off on a rampage and instead of calming her down ... [I] would set her off even worse."
Peterson and Savio's divorce proceedings were made final in 2002. Savio then wrote to Illinois assistant state attorney Elizabeth Fragale, expressing fears that Peterson might kill her.
Peterson discovered Savio's body in her Illinois home while married to his fourth wife, Stacy Peterson.
"I heard screaming upstairs and her friend Mary went upstairs and she was dead in the bathtub," Peterson said. "I checked for life signs and I knew at that particular time I didn't belong there, so I called for additional police units to show up and take charge of the scene."
An autopsy revealed Savio had fallen into the bath and drowned. Once Stacy Peterson went missing, police exhumed Savio's body and concluded she had been murdered.
Peterson has said Stacy decided to leave him in 2007 for someone else.
"She said she was leaving," Peterson said. "She found somebody else. She'll be gone for a while."
Police investigating her disappearance found an e-mail to friends written before she vanished in which she confided to being in a "controlling, manipulative and somewhat abusive" relationship.
Peterson has said "that doesn't even sound like something she would say," adding, "I really question the origin of that e-mail."
Stacy's friend Pam Bosco claims to have been told by Stacy, "I love you. If anything happens to me, he killed me. It wasn't an accident."
ABC News' Martin Bashir, Eric Johnson and Katie Escherich contributed to this report.