Kristen Anderson moved into Savio's house after Peterson and Savio split up. She testified on Wednesday that Savio had told her Peterson bragged, "I could kill you and make it look like an accident."At that point, Anderson broke down on the stand and had to leave the courtroom. When she returned, she spoke about an incident Savio told her about. Anderson said that Peterson, dressed in SWAT gear, broke into the home and, holding a knife to Savio's throat, threatened her.
"She showed me a knife that she kept in between her mattresses for protection," Anderson said.
Savio's body was found in her bathtub in 2004. At first ruled an accident, the case was reopened when Peterson's fourth wife, Stacy Peterson, disappeared in 2007. That led to the murder charges against the ex-Bolingbrook police officer.
Anderson said she called police three times about Savio's case in 2004, but those calls were never returned.
During cross-examination, defense attorney Joe Lopez raised his voice, pressing Anderson repeatedly about why -- if the threat was so unsettling -- she didn't move out of Savio's house.
"You didn't move out, did you? ... You did nothing ... because you didn't believe her, that's why," Lopez shouted over the objection of prosecutors.
"Sir, no one listened to Kathy," Anderson added later.
Judge Edward Burmila handed prosecutors the legal victory by allowing Anderson's hearsay testimony. At first, the judge seemed to signal he would bar it, prompting an angry James Glasgow, the Will County state's attorney, to raise his voice.
"This evidence should have life!" the normally monotone chief prosecutor shouted. The jury was not in the room.
With no physical evidence at their disposal, hearsay statements like Anderson's are at the heart of the prosecution's presentation to jurors. Without them, most legal experts say the state stands virtually no chance of a conviction.
Burmila, who once lost a political race to Glasgow, criticized the prosecution for poorly addressing the complex legalities surrounding hearsay, but surprised many -- even eliciting gasps -- by allowing then testimony.
Addressing reporters at the end of the day, Glasgow was clearly thrilled the ruling had gone his way.
"Judge Burmila made an historical ruling today," he said.
Lopez said his client was disappointed in the ruling.
"He's upset," Lopez said. "But you have to deal with the cards they give you."
Earlier in the day, the 58-year-old Peterson sat forward attentively while Collins was on the stand, once standing and appearing to suggest a question to his attorney.
Investigator: Peterson sat in on Stacy's interview
As a ''courtesy'' to a fellow officer, Drew Peterson was allowed to sit with Stacy while police questioned her shortly after Kathleen Savio was found dead.
Peterson, who was divorcing Kathleen Savio at the time of her death, is charged with her murder. Prosecutors are trying to show that police botched the investigation in 2004, at which time Savio's death was ruled accidental. After Stacy disappeared, officials reopened the Savio case and charged Peterson with murder.
Retired Illinois State Police Sgt. Patrick Collins led the 2004 investigation. He said Wednesday that Savio's death "appeared accidental" when he arrived on the scene. He also interviewed Drew and Stacy that day.
"I asked him if he knew why I was interviewing him. He said, 'Yes.' I asked him how their divorce was going. He said, 'Good,'" Collins said. ""He told me their relationship was found pretty good despite the fact that they were in the last stage of the divorce."
Collins said he then interviewed Stacy at the Peterson home with Drew sitting next to her as a courtesy. He said the two sat very close together and Drew had a hand on her Stacy's leg.
Prosecutors are trying to show that in 2004 police failed to collect forensic evidence, interview Savio's relatives or secure the home where her body was found. Prosecutors are seeking to show that evidence was brought to justify their reliance on evidence and hearsay testimony.
"The investigation was properly done. They have no evidence that it was botched. Secondly, even if you assume there were problems with the investigation, has that led to one shred of evidence against Drew? No," defense attorney Steven Greenberg said.
Judge denies motion to strike testimony
Before the sixth day of testimony in the murder trial began on Wednesday, the judge denied a defense request to strike testimony from one of Peterson's colleagues. On Tuesday, Bolingbrook Police Lieutenant James Coughlin said Peterson told him, "My life would be easier if she were just dead."
Peterson's defense team wanted that testimony struck from the case. "That conversation never took place," Greenberg said.
The judge denied their request.
Peterson was only charged in Savio's death after his fourth wife, Stacy Peterson, disappeared in 2007. He has denied any wrongdoing.
The Associated Press contributed to this report. All rights reserved.