A man who was imprisoned for 36 years walked free Thursday after a U.S. federal judge threw out his murder conviction and life sentence for a newspaper editor's stabbing in the French Quarter of New Orleans.

During a brief hearing, U.S. District Judge Sarah Vance formally signed off on the release of John Floyd. He walked free minutes later, wearing a black T-shirt with the word "Justice" written on it.

"This T-shirt tells it all," he said in a soft voice, flanked by his attorneys outside the courthouse. "I never lost hope. I knew one day it would come."

He added, "It will take me a while to get used to it. It feels good."

Vance's order says Floyd will live in Carencro, La., on supervised release. One of Floyd's attorneys said he will work on a farm there.

In May, Vance had ordered prosecutors to either retry Floyd or release him within 120 days.

District Attorney Leon Cannizzaro's office agreed to Floyd's release while it appeals the judge's earlier decision to toss out his 1982 conviction.

Evidence confession was coerced

Vance ruled in September that no reasonable juror would find Floyd guilty of murder based on all the evidence in the November 1980 stabbing death of William Hines, a Times-Picayune copy editor.

Floyd had confessed to killing Hines and another man — three days and 1½ kilometres apart and under similar circumstances. But the judge said new evidence supports Floyd's claim that police beat him to coerce a confession.

Vance said Floyd's conviction was based entirely on his statements to police investigators, who didn't uncover any physical evidence or eyewitness testimony linking Floyd to the crime scene.

Floyd, now 67, was a 32-year-old "drifter" living in the French Quarter when Hines and Rodney Robinson, a businessman, were stabbed to death. Both victims were gay and were killed after apparently sharing a drink and having consensual sex with their attacker.

Police found Hines's body in his bedroom on Nov. 26, 1980, and believed he was killed a day earlier by a welcomed visitor. Robinson's body was found Nov. 28, 1980, in the hallway of a downtown hotel.

Floyd has been in custody since January 1981, when police arrested him at a French Quarter bar. Floyd testified that a police detective, John Dillman, and another officer bought him five or six beers at the bar before his arrest.

Floyd also testified that Dillman beat him during his interrogation after he initially denied killing Hines or Robinson.

A judge acquitted Floyd of murder in Robinson's killing, but convicted him of second-degree murder in Hines's death.

In her ruling last year, Vance said physical evidence at the scene of Robinson's death excluded the possibility that Floyd killed him "in the manner described in his confession." Instead, the evidence pointed to a killer of a different race and blood type than Floyd.

"If Floyd was willing — for whatever reason — to falsely confess to one murder, it is far more likely that his other confession is false as well," the judge wrote. "The considerable evidence tending to undermine the Robinson confession, therefore, also serves to undercut the Hines confession."

The National Registry of Exonerations has examined 2,049 exonerations in the U.S. since 1989 and found it included 245 cases of innocent men and women who confessed, according to registry senior researcher Maurice Possley. Nearly 75 per cent of those false confessions were in homicide cases, Possley said in an email.

Prosecutors have claimed that before giving written confessions to police, Floyd had "freely boasted" that he killed both men after picking them up in French Quarter gay bars.

"He twice presented evidence during his initial prosecution to prove that Det. Dillman had beaten his confession out of him, which the trial court failed to find credible either time," Assistant District Attorney Andrew Pickett wrote in a 2012 court filing.

Floyd's attorneys said he couldn't read the confessions he signed, has an IQ of 59 and a "highly suggestible personality," leaving him vulnerable to giving a false confession.

"The state of Louisiana has inflicted a grave injustice on a vulnerable citizen in violation of the constitution and, when presented with evidence of this, has utterly failed to acknowledge or remedy the injustice," his attorneys wrote in a 2011 court filing.