A prison inmate Drew Peterson is accused of enlisting to arrange the killing of a state's attorney says the imprisoned former suburban Chicago police officer also admitted to killing his missing fourth wife.

Antonio Smith testified Monday that the ex-Bolingbrook sergeant convicted in 2012 of killing his third wife referred to Stacy Peterson as a "dead woman" and said he killed her, the Chicago Tribune reported. Peterson also asked for help hiring a hit man to kill Will County State's Attorney James Glasgow, who put Peterson behind bars, Smith testified.

Peterson, 62, has never been charged in Stacy Peterson's disappearance and has maintained his innocence.

He's serving a 38-year sentence in the 2004 death of his ex-wife Kathleen Savio in a case that was reopened after Stacy Peterson went missing in 2007.

Randolph County State's Attorney Jeremy Walker told jurors on the first day of Peterson's murder-for-hire trial that the defendant was motivated by "anger, hatred (and) revenge" against Glasgow, as well as the belief that the prosecutor's death would lead to a successful appeal of his first-degree murder conviction, which is under review by the Illinois Supreme Court.

Smith -- whose prison nickname is "Beast" -- testified that Peterson said he was owed $10,000 that would be his payment to "the person that was supposed to do the killing," according to the Tribune.

Smith reported the offer to authorities and agreed to help secretly record Peterson, according to prosecutors. Those wiretapped conversations are expected to be played in court during the weeklong trial.

Peterson, who is imprisoned at the Menard Correctional Center in southern Illinois, has pleaded not guilty to charges of solicitation of murder for hire and solicitation of murder related to Glasgow. He faces an additional 60 years in prison if convicted of those charges.

"They're going to sensationalize the heck out of this thing," defense attorney Lucas Liefer told the jurors during his opening statement. "Do not give in to this approach."

Peterson's animus toward Glasgow -- whom Walker said Peterson wanted killed on the elected prosecutor's way to or from his Joliet office -- extended beyond Glasgow's role in helping put him behind bars, according to testimony and evidence presented.

On the recordings, Peterson blames Glasgow for efforts to revoke Peterson's $79,000 annual police pension, prosecutors say. He also says Glasgow is the reason that Peterson's son, Stephen, lost his job at the Oak Brook Police Department over what authorities said were the younger Peterson's efforts to obstruct the investigation into Savio's death.

After Peterson's conviction, Glasgow called him a "coward" and a "thug" who would "threaten people because he had a gun and a badge."

Glasgow testified that he listened to about 15 minutes of the Peterson wiretap.

"The word 'kill' wasn't used, but the implication of kill was there," Glasgow testified. "Based on 36 years of experience in law enforcement, from my listening of the tape, it was clear to me there was going to be my demise."

Walker said Smith, the prison informant, didn't receive a reduced sentence for his cooperation but was paid $3,200 by the FBI to replace property lost after he was transferred to the federal prison system following his involvement with Peterson.