At a pre-trial hearing, Kristin Anderson said that Savio also kept a kitchen knife under her mattress. Anderson and her family lived in Savio's house for a couple of months in 2003.
Anderson also testified about an incident in which Peterson reportedly put a knife to Savio's throat and threatened to kill her.
Anderson said she contacted Illinois State Police after Savio's death but they never responded.
The pre-trial hearing will determine what hearsay evidence can be used in Peterson's murder trial.