Testifying at a hearing to determine what hearsay evidence will be admissible in Peterson's murder trial, Dr. Jeffrey Jentzen said he believed Savio died as a result of an accidental fall in 2004 and was not murdered, the Chicago Tribune reported.
Jentzen, the director of autopsy and forensic services at the University of Michigan Medical School, was the first witness called by attorneys for Peterson, a former Bolingbrook, Ill., police sergeant.
Savio's death had been ruled accidental but the investigation was re-opened after Peterson's fourth wife, Stacy Peterson, disappeared. Savio's body was exhumed and, following an autopsy, investigators concluded she had been killed.
Jentzen, who did not perform an autopsy on Savio, testified his conclusion was based on a review of documents and photographs, and his understanding that the deputy coroner, a pathologist and a state police crime scene investigator all agreed Savio's death was accidental.
"It's my opinion that it's an accidental death," he testified.
Closing arguments in the pretrial hearing are expected Friday, the Tribune said.