(CBS) — Drew Peterson will be sentenced on Friday for trying to hire someone to kill the prosecutor who helped to convict him in the killing of his third wife.

Peterson was convicted of trying to hire a fellow inmate’s uncle while in prison to kill Will County State’s Attorney James Glasgow, who helped convict Peterson in 2012 of killing ex-wife Kathleen Savio eight years earlier. Prosecutors say Peterson believed that with Glasgow dead, he could win an appeal of his conviction.

READ MORE: 3 Killed, 21 Wounded In Weekend Shootings Across Chicago, Including Mass Shooting In Chatham

Peterson faces up to 60 years in the Glasgow plot. He is serving 38 years for murdering Savio.

Peterson’s fellow inmate, Antonio “Beast” Smith, wore a wiretap for prosecutors, and jurors heard hours of Smith’s recorded conversations with Peterson at Menard Correctional Center in November 2014. Smith testified last week that Peterson enlisted him to help kill Glasgow.

READ MORE: 1 Killed, 9 Others Injured In Mass Shooting On South Side

In one recording, Smith tells Peterson that he gave his uncle the go-ahead to kill Glasgow.

“OK, all right, I’m in,” Peterson, a former Bolingbrook police sergeant, responded. “From the first time we talked about it, there was no turning back.”

Savio’s death was initially deemed accidental. Glasgow reopened the case after the 2007 disappearance of Stacy Peterson, Peterson’s 23-year-old fourth wife.

MORE NEWS: Treyvon Marks, 26, Charged In South Loop Carjacking

Peterson was never charged in her disappearance but told the informant he worried that Glasgow would eventually do so.