Judge Edward Burmila was expected to rule Wednesday, the Chicago Tribune reported.
Peterson, a former police officer in Bolingbrook, Ill., is charged with killing his ex-wife Kathleen Savio, who was found dead in her bathtub in 2004. The death was ruled accidental at the time but a new investigation was opened when his fourth wife, Stacy Peterson, vanished in 2007.
Will County Assistant State's Attorney Kathleen Patton was questioning Teresa Kernc, a retired Bolingbrook police lieutenant, when she asked her about an order of protection Savio applied for. Burmila had ordered lawyers not to introduce the topic.
Patton, distraught, apologized several times: "Judge, that was my fault. I don't know what else to say."
Kernc, the fourth witness to mention the incident, described Savio's story. She said Savio reported her estranged husband, dressed in his SWAT uniform, surprised her in her home and kept her there for 3 hours.
"When she tried to rise, he pushed her down again," Kernc said. "He told her she was a mean bitch, she wouldn't speak to him when he called, wouldn't speak to him when he brought the boys over, and he was going to speak to her now."
Kernc said Savio decided not to get an order of protection because she was afraid Peterson would be fired.