A former suburban Chicago police officer jailed for killing his wife received a 40-year prison sentence Friday for plotting to kill the prosecutor who helped convict him of murder in 2012.

Drew Peterson was found guilty in May of attempting to hire a hitman to kill Will County State’s Attorney James Glasgow.

Peterson was sentenced to 38 years in prison for killing his third wife, Kathleen Savio. Prosecutors say that while serving his sentence, Peterson approached a fellow inmate about the possibility of hiring someone to kill Glasgow. 

The inmate, Antonio Smith, agreed to wear a wire for investigators and recorded Peterson offering $10,000 to hire Smith's uncle to kill Glasgow. 

In court Friday, Peterson claimed that he knew he was being recorded and had never meant to kill Glasgow, but was pretending to order the hit so Smith could turn him in and receive a reduced sentece. He added that at the time of the recordings, in November 2014, he was suicidal and didn't believe he would live to see the scam come to fruition.

"Jim Glasgow, there was never any intent to have you killed," Peterson said. Glasgow responded outside the courtroom by calling Peterson "deluded" and "a patronizing con man."

In court, Glasgow said that a lengthy sentence was necessary as a deterrent, otherwise convicts will believe they can kill a prosecutor and get the minimum sentence.

"It's critical that a message be sent that this will never be (allowed) in Illinois," he said.

The Chicago Tribune reported that Friday's sentence, which must be served after Peterson's sentence for killing Savio, essentially guarantees the 62-year-old Peterson will die in prison. He had been scheduled for parole in 2047.

Peterson first came to national attention in 2007 after his fourth wife, Stacy, vanished from their home in Bolingbrook, Ill. She has never been found and no one has been charged in connection with the case. However, Peterson was recorded telling Smith he was worried that Glasgow would eventually charge him in the case.

Kathleen Savio was found dead in her bathtub in 2004. Her death was initially ruled an accident, but Glasgow ordered the case re-opened following Stacy Peterson's disappearance.

The Associated Press contributed to this report.

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