CHICAGO (CBS) — A 64-year-old man who was freed from prison last year, after prosecutors dropped charges in a 1982 double murder case, has filed a $40 million lawsuit against Northwestern University, accusing a former professor and his team of railroading him into a false confession.

Alstory Simon, 64, spent more than 15 years behind bars, after he confessed to killing Marilyn Green and her fiancé Jerry Hillard in 1982.

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His videotaped confession led to authorities dropping charges against Anthony Porter, who was on death row in 1999, and less than 48 hours away from being executed before he was freed.

However, Simon has since claimed he only confessed and pleaded guilty because he was told he’d serve a short time in prison, and would get rich from book and movie deals. He was sentenced to 37 years in prison, but later recanted.

He has sued the university, former professor David Protess, private investigator Paul Ciolino, and former Simon defense attorney Jack Rimland, seeking $40 million in damages.

“He needs to be compensated for having 16 years taken out of his life. Some of the best years of his life were spent incarcerated,” said Simon’s attorney, Terry Ekl.

Ekl and Simon have accused Ciolino — who was working for Protess when he taught an investigative journalism class at Northwestern — of using threats, intimidation, and false promises of money to get a false confession from Simon.

“The coercive tactics that were involved. The fact that the confession was, in fact false,” Ekl said.

Simon has said Ciolino put a gun to his head while questioning him about the case.

Simon was freed in October after the Cook County State’s Attorney’s office dropped charges.

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Ekl has said Protess and Ciolino saw Porter as a potential poster boy for the anti-death penalty movement, and needed someone else to take his place in prison.

Ekl said Northwestern allowed the coercion because it led to national recognition for the university.

The university has issued a statement, saying it’s reviewing the allegations and that it denies all wrongdoing and looks forward to being vindicated.

Cook County State’s Attorney Anita Alvarez began reviewing Simon’s conviction in 2013, and dropped charges against him last year.

Alvarez said Protess and Ciolini used “alarming tactics” in their efforts to clear Porter’s name, including having actor to speak to Simon, pretending to be a witness to the shootings.

Alstory Simon Lawsuit

Calling Ciolini a “rogue investigator to obtain Simon’s confession, she said he came to Simon’s home with “guns drawn,” posing as a police officer.

Alvarez said, to this day, some witnesses maintain Porter was the shooter, although she stopped short of saying she believes he was the killer.

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Porter was pardoned by former Gov. George Ryan, so Alvarez could not pursue new charges against him, even if she wanted to.