A pathologist who concluded that the death of Drew Peterson's ex-wife was a homicide and not an accident as first determined testified Friday that her injuries weren't consistent with a fall in a bathtub.

Dr. Larry Blum, in his first public comments since the 2007 autopsy of Kathleen Savio, said he didn't think bruises on her body and a laceration to the back of her head came from a single fall. Savio's body was found slumped forward in a dry bathtub in 2004, and Blum said that her position wasn't consistent with a fall in the tub.

"There was no blood, hair or tissue on the tub," he said. "So the evidence doesn't bare that out."

Blum said Savio did drown but her death was not accidental, as another pathologist initially found.

"It was my opinion that it was a homicide," Blum said.

Peterson, a 56-year-old former Bolingbrook police officer, has pleaded not guilty to first-degree murder in the death of his third wife, Savio. Her body was exhumed in 2007 following the disappearance of Peterson's fourth wife, Stacy Peterson. Drew Peterson has not been charged in Stacy Peterson's disappearance, but authorities say he is a suspect.

Blum's findings will be at the center of the courtroom battle between Will County prosecutors and Peterson's attorneys, who argue that Savio's death was accidental.

Blum testified at a hearing to determine what hearsay evidence will be allowed at Peterson's upcoming trial. Hearsay, or statements not based on the direct knowledge of a witness, usually isn't admissible in court. But Illinois judges can allow it in murder trials if prosecutors prove a defendant may have killed a witness to prevent him or her from testifying.

There's little available forensic evidence in Savio's case, so prosecutors are expected to rely on statements Savio allegedly made to others saying she feared Peterson could kill her.

Blum, who said he laid down in Savio's tub as part of his investigation, testified the injury to the back of Savio's head may have been made shortly after her death and not as a result of a fall. He also pointed to a wound in the area of Savio's diaphragm as one that wouldn't have been caused in a fall.

"The bruise was deep, down to the bone," he said.

He also agreed with Will County State's Attorney James Glasgow's suggestion that the diaphragm injury might have been caused by what Glasgow called a "bear hug."

Blum also testified that Savio had no measurable drugs or alcohol in her system when she died — an effort to head off the argument defense attorneys have raised that perhaps Savio was in a condition that would have made a fall more likely.

Earlier in the day, Mary Parks, who studied nursing with Savio, testified about a day in late 2003 when Savio showed her red marks on her neck and told her Peterson made them.

"She told me her ex-husband had come into the house and had pinned her down," Parks testified.

Parks said Savio told her that during the incident Peterson told Savio, "Why don't you just die?"

She also said that Savio told her Peterson was intent on leaving her with nothing in the couple's divorce — but that even leaving her without any money, a share of the business the two owned, child support or custody of their two sons wouldn't have been enough for him.

"Kathy was very sure that if she gave up every cent ... that her ex-husband still would not leave her alone," Parks said.

Parks said she contacted prosecutors after Savio was found dead but was told there was no investigation into the case.