Updated

Drew Peterson's stepbrother fears that he had a hand in the murder of the former Illinois police sergeant's fourth wife, Stacy Peterson — telling a Chicago-area newspaper that he helped Drew Peterson dispose of a blue barrel that may have contained Stacy's remains.

Stacy Peterson disappeared in October 2007. Her husband has been the focus of a police and grand jury investigation, but he never has been charged.

Thomas Morphey, the stepbrother, told the Herald News that he thinks Stacy, 23, was in the blue barrel that he helped remove from the Petersons' home in Bolingbrook, Ill., and put into a car.

Beforehand, Morphey told the Herald News, Peterson, 55, had come to his home to take him to a nearby store where Peterson supposedly had set up an interview for him. But instead, the two went to a park, where a conversation led him to believe Peterson was planning to murder Stacy's boyfriend, Morphey said.

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“We went to that park to discuss Stacy cheating on him, and he had to take care of the problem,” Morphey told the newspaper. "I didn’t think for a minute he was going to try to kill her.”

Peterson started questioning Morphey's love for him and asked if he would kill for him.

When Morphey said no, Drew Peterson allegedly asked, "Could you live with knowing about it?"

Morphey told the newspaper that he responded, "Yeah, I guess," adding that he always figured Peterson had killed his third wife, Kathleen Savio.

Savio's death in a bathtub was ruled a homicide after initially being deemed accidental. Savio's body was exhumed and re-examined after Stacy Peterson vanished.

Morphey told the Herald News that the night after meeting Peterson in the park, he met up with Peterson, who enlisted his help with the blue barrel.

Morphey was offered immunity by police to tell them what happened that night, but has yet to tell it to a grand jury, he said.

Peterson insists Morphey is lying.

"He’s hallucinating," he told the newspaper.

Click here to read more on this story from The Herald News.