Jurors deliberated for about 14 hours before reaching their decision.
Savio family says Stacy Peterson is "next for justice."
Drew Peterson, a former Bolingbrook police sergeant, awaited trial for more than three years on charges he killed his third wife, Kathleen Savio.
As deliberations reached the 12-hour mark in the Drew Peterson murder trial, jurors came back Thursday with another question, their fifth.
9/6/2012: Cassandra Cales expresses hope that the first-degree murder conviction against Drew Peterson leads to information that helps find her sister, Stacy Peterson.
Jurors, not dressed in matching outfits Wednesday, received instructions for two counts of first-degree murder.
Each team was given roughly two hours to state their case to the seven man, five woman jury that's already sat through five weeks of testimony.
Ruling came after about four hours of debate between prosecutors and defense attorneys over jury instructions
Savio's divorce attorney dances around issue of Stacy Peterson's disappearance.
College sophomore testified Wednesday in father's murder trial.