(CBS) -- Perhaps you have seen the sign: "Free Matt Sopron."
It's off Stevenson Expressway near the Harlem Avenue exit. So, who is he? Where is he? And why are people trying to free him?
CBS 2's Rob Johnson reports.
To get answers, you have to head nearly five hours south to Menard Correctional Center, where 41-year-old Matt Sopron has spent nearly half of his life in prison.
Johnson recently spoke to Sopron by phone. He says he can't figure out why he's behind bars.
It started in 1995 when members of the Almighty Popes gang gunned down two teen girls in a van. Police arrested several suspects, including Billy Bigeck. Matt Sopron, also a member, wasn't arrested until nine months later.
Why does Sopron think he's the guy that's going down for this?
"Well, Bigeck brought my name up," Sopron tells Johnson.
Bigeck and two others -- John Gizowski and Bryan O'Shea -- named him as the gang leader, claiming he ordered the hit on the van.
Sopron's prior record didn't help.
"I got convictions such as gang activity and graffiti and minor assaults," Sopron says.
Pat Walsh defended Sopron.
"I felt like we won every day at trial. I think we showed that the witnesses had lied," Walsh says.
"We were devastated, but we never believed it. Never," the inmate's mother, Patricia Sopron, says.
Since his conviction, three witnesses have recanted their testimony. Bryan O'Shea first approached Walsh in 2000 to change his story.
"It's the worst thing I've ever done in my life, hands down, but the best thing I've ever done was come out with the truth," O'Shea says.
He says he lied on the stand after being coerced by the assistant state's attorney.
"So, he's scrambling the brains in my head so the second I say a lie he goes, 'Oh great, now we're getting to the truth'," O'Shea says.
In a 2001 affidavit, Gizowski testified he "never witnessed Matthew Sopron or anyone else give any orders to shoot or hurt anyone."
And in notes Pat Walsh took in a 2016 interview, Bigeck says his testimony at trial "wasn't true, it was a lie."
Johnson tracked down former Assistant State's Attorney Scott Cassidy. Cassidy declined comment, other than to say it's not true he threatened the witnesses so that they would testify against Sopron.
Sopron has appealed three times and has another appeal forthcoming. His family remains hopeful that one day he will leave prison.
Patricia Sopron said she believes it will happen.
"The truth will be seen. And, that's what he lives by, and as a result he's given us strength," she says.
In the past few months, two other men convicted in the shooting have told attorney Walsh that Matt Sopron had nothing to do with the murders, including the actual shooter.
Sopron's case is now being reviewed by Cook County's Conviction Integrity Unit.
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