Prosecutors said the ex-cop and convicted murderer Drew Peterson knew how to stage a crime scene -- and once-secret recordings showed he himself wasn't fooled by a staged photo meant to show progress in his alleged plot to kill an attorney who helped put him behind bars.

Fellow prison inmate Antonio Smith, otherwise known as "Beast," showed Peterson the photo while wearing a wire, investigators said in court Wednesday. In one recording, Peterson was heard saying, "I mean, are you kidding me? ... It looks like it was staged -- 'Here, you stand here."'

"Beast" testified that the photo showed Will County, Ill. State's Attorney James Glasgow standing outside his office in Joliet, with an assistant and an FBI agent dressed up to look like one of the informant's relatives.

Peterson's murder-for-hire trial started on Monday. Prosecutors said the defendant, now 62, tried making plans to kill Glasgow in retaliation for his 2012 murder conviction.

The former Bolingbrook police sergeant's third wife, Kathleen Savio, turned up dead in a dry bathtub in 2004. Investigators initially said she accidentally drowned, but ruled her death a homicide after his fourth wife, Stacy Peterson, vanished in 2007.

During his murder trial, prosecutors said Drew Peterson staged the crime scene to make Savio's death appear accidental. He denied murdering her and pleaded not guilty in his current trial.

Peterson faces another 60 years on top of his 38-year sentence if convicted in the current case. His first-degree murder conviction is under appeal to the Illinois Supreme Court. Prosecutors claimed Peterson hoped to win a reversal of the case once Glasgow was dead.

Investigators never found Stacy Peterson's body. "Beast" said in court that the defendant admitted he killed her.

"Beast," a Chicago gang member, was sentenced to 40 years for attempted murder, home invasion and robbery.

The Associated Press contributed to this report.