A former Illinois police sergeant who is serving time for killing his third ex-wife was found guilty on Tuesday of trying to hire a hit man from prison to murder the prosecutor who put him behind bars.

Following a six-day trial, a jury convicted Drew Peterson, 62, of solicitation of murder for hire and solicitation of murder for a plot to kill Will County State’s Attorney James Glasgow, Attorney General Lisa Madigan said in a statement. Peterson was serving a 38-year sentence for his wife’s death after a 2012 conviction when he tried hiring someone to kill Glasgow between 2013 and 2014, CNN reports.

His sentencing is set for July 26. He faces 20 to 40 years in prison for solicitation of murder for hire and 15 to 30 years in prison for solicitation of murder.

“The evidence in this case was clear that the defendant plotted from jail to solicit the murder of State’s Attorney Jim Glasgow,” Madigan said. “I thank the members of the jury for their service, and I commend the prosecutors for their hard work and relentless commitment to bringing this case to a successful conclusion.”

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