That was particularly evident when Peterson's stepbrother took the stand at a hearing Thursday regarding the death of the third wife, Kathleen Savio. He spoke for three hours about the day wife No. 4, Stacy Peterson, vanished -- and told of helping Peterson handle a barrel he thinks may have contained Stacey Peterson's body.
Peterson, a former Bolingbrook, Ill. police officer, has pleaded not guilty to first-degree murder in the death of Savio, whose body was found in a dry bathtub in her home in 2004. Peterson hasn't been charged in Stacy's 2007 disappearance, but authorities say he is the only suspect.
Prosecutors did not immediately explain why they asked Peterson's stepbrother, Thomas Morphey, to testify about Stacy Peterson at such length during a pretrial hearing meant to decide what, if any, "hearsay" evidence prosecutors can use to try to prove allegations that Peterson killed Savio. Will County state's attorney's spokesman Chuck Pelkie said it would become clear later.
CBS News legal analyst Lisa Bloom says, "It has to be to show pattern because, in this hearing, which is really a trial before the trial, the state has to show that Drew Peterson killed Kathleen Savio. And I believe at the trial, they'll be allowed to introduce evidence as to both (wives), to show it was a pattern, that he killed them, according to the state, to prevent them from divorcing him and taking a lot of his money."
Whether the hearsay evidence is admitted could prove pivotal, Bloom adds, explaining to "Early Show" co-anchor Maggie Rodriguez Friday, "That's what it's all about. She allegedly told about 15 people, 'He's threatened me, he held a knife to my throat, he's going to kill me, he's going to get away with it, he's going to make it look like an accident.' (That's) critical evidence for the state. They want to get that evidence in, and that's the basis of this hearing. At the end of this hearing, in about a month, the judge will decide whether those statements can come in or not."
Without them, Bloom observes, prosecutors would have "a significantly weakened case, because I think those statements are the strongest part of the state's case. Without it, there's no forensic evidence linking Drew Peterson to the killing of Kathleen Savio and he's got an alibi: He says he was home with a lot of family members the entire weekend that she was killed."
Friday's testimony was likely to turn to the day Savio's body was found. The lead Illinois State Police investigator who originally looked into Savio's death, retired Sgt. Patrick Collins, was scheduled to resume testifying and was expected to explain why the death was initially ruled an accident.
Officials decided to exhume Savio's body after Stacy Peterson's disappearance. A subsequent autopsy concluded Savio was the victim of a homicide.
At Thursday's hearing, Morphey described in detail how he believed he might have helped his relative dispose of Stacy Peterson's body. She has not been seen for more than two years.
Morphey said Drew Peterson suggested when they talked on Oct. 27, 2007, that he intended to kill his fourth wife because she planned to divorce him, win custody of their children and take Peterson's money.
Morphey said he drank heavily the next day.
"I just heard someone was going to murder somebody else," Morphey explained.
Peterson brought Morphey back to his Bolingbrook home, Morphey said, went into a master bedroom and rolled out a large blue barrel that Morphey estimated weighed up to 150 pounds.
Morphey stopped short of saying Peterson directly admitted murdering Stacy and he said the two men never talked about what was in the barrel. Morphey also testified that he had told Peterson that he always assumed he had killed Savio, but that Peterson denied it.
The story of the blue barrel has been central in Stacy Peterson's case. Numerous search parties over the years, including divers, have focused on finding it, but it has never turned up.
Morphey testified that he had not wanted to help Peterson, in part because he didn't want anything to do with what he thought Peterson did. Morphey did not explain why he agreed to help.
According to his testimony, the two men took the barrel, put it in Peterson's SUV; Peterson then drove Morphey home.
"He said, 'This never happened,"' Morphey testified. "I said, 'I won't tell a soul."'
Nevertheless, Morphey said he later told his girlfriend, brother and a neighbor. And he said he was stressed and drinking more than normal. The anxiety, Morphey said, even led him to overdose on the anti-anxiety drug Xanax in an attempt to end his life.
"I felt everything was coming down on me," he said. "I'm still scared to death."
Under cross-examination, Peterson's attorneys raised questions about Morphey's mental state and whether was a credible witness.