Simmons had served 48 years, one month and 18 days, almost half a century; in prison for the murder of Carolyn Rogers during a liquor store robbery in an Oklahoma City suburb.
In an order on Tuesday, Oklahoma County District Judge, Amy Palumbo, exonerated Simmons.
“This court finds by clear and convincing evidence that the offence for which Mr. Simmons was convicted, sentenced and imprisoned… was not committed by Mr. Simmons,” Palumbo said in a ruling.
Reacting to the judgment, Simmons said, “It’s a lesson in resilience and tenacity,” Mr Simmons told reporters after the decision, according to the Associated Press. “Don’t let nobody tell you that it can’t happen, because it really can.”
At the time of his arrest, Simmons was 22 years old – making him the longest-serving inmate to be cleared, according to the National Registry of Exonerations.
Simmons and his co-defendant, Don Roberts, were convicted in part because of testimony from a teenager who had been shot in the back of the head. The teenager pointed to several other men during police line-ups.
They were both convicted and sentenced to death in 1975. However, due to US Supreme Court rulings on the death penalty. their death sentence was later reduced to life in prison.
Roberts was released on parole in 2008.
Simmons had said he was in his home state of Louisiana at the time of the murder.
A district court vacated his sentence in July after finding that prosecutors had not turned over all evidence to defence lawyers, including that a witness had identified other suspects.
Wrongfully convicted people who serve time in Oklahoma are eligible for up to $175,000 (£138,000) in compensation.
However, one of Simmons’ attorneys, Joe Norwood, added that Simmons is living off of donations, primarily from GoFundMe, while he’s undergoing cancer treatment, USA Today reported.
“Whatever compensation he has coming is down the road, but I would just encourage people to donate to Glynn’s GoFundMe because money ain’t showing up in his bank account tomorrow,” Norwood said.
Norwood said the state of Oklahoma wrongfully took a chunk of his life away.
“He had 50 years stolen from him, the prime of his work life when he could have been getting experiences, developing skills. That was taken from him, by no fault of his own, by other people,” he said.
