Joel Brodsky, one of the former Bolingbrook police officer's lawyers, made the reference in his opening statement, the Chicago Sun-Times reported.
"Stacy Cales Peterson is missing for some unknown reason," Brodsky said.
That disappearance in 2007 may be why Peterson is on trial now, the newspaper said. His third wife's death in 2004, after their divorce and his remarriage, had been ruled an accident, but police three years later began listening to Kathleen Savio's friends, who reported threats her ex-husband had made, and reopened the investigation. A second autopsy concluded that Savio, found dead in her bathtub, was a victim of homicide.
During testimony from Savio's friends, defense lawyers have questioned them on why they did not pursue their suspicions. On Wednesday, Judge Edward Burmila ruled that Joseph Lopez had opened the door when he grilled Kristin Anderson about her testimony that Savio had told her Peterson threatened her while wearing a SWAT uniform, saying he could kill her and make it look like an accident.
Will County State's Attorney Jim Glasgow decided, apparently for strategic reasons, not to walk through the door, at least not yet. Stacy Peterson's family hopes the disappearance will come up, the Sun-Times reported.
"I'm just waiting for that door to be cracked wide open not by the state but by the defense," Pamela Bosco, a family spokeswoman who has been in court every day, was quoted as saying. "Again, everyone wants to know why nobody did anything up until 2007."
Peterson says his fourth wife left him. Five years later, she is still missing, and he faces no charges in connection with her disappearance.
Notable deaths of 2014 [PHOTOS]