A man who spent nearly three decades on death row in a Louisiana prison has been freed after prosecutors asked a judge to set aside his first-degree murder conviction and death sentence.

Prosecutors cited new evidence in the case that exonerated 64-year-old African-American Glenn Ford, who was convicted by an all-white jury for a 1983 robbery and murder.

Isadore Rozeman, a watchmaker, was found shot dead behind the counter of his jewellery shop in Shreveport.

Acting on new information that exonerated Mr Ford, a judge in Shreveport ordered him released from Louisiana State Penitentiary in Angola.

Mr Ford, who had been held on death row since March 1985, was released yesterday evening.

"We are very pleased to see Glenn Ford finally exonerated, and we are particularly grateful that the prosecution and the court moved ahead so decisively to set Mr Ford free," said Gary Clements and Aaron Novod, attorneys for Mr Ford from the Capital Post Conviction Project of Louisiana.

Mr Ford, a California native who did occasional yard work for Mr Rozeman, was found guilty in 1984 and was sentenced to die by electrocution, then the state's method of execution.

For three decades, Mr Ford maintained his innocence and filed multiple appeals, most of which were denied.

But in 2000, the Louisiana Supreme Court ordered an evidentiary hearing on Mr Ford's claim that the prosecution suppressed favourable evidence related to Jake and Henry Robinson, two brothers initially implicated in the crime.

According to the Shreveport Times, court records show that an unidentified informant in 2013 told prosecutors that Jake Robinson admitted to shooting and killing Mr Rozeman.

Last Thursday, prosecutors filed a motion to vacate Mr Ford's conviction and sentence, saying that in late 2013 "credible evidence" came to their attention "supporting a finding that Mr Ford was neither present at, nor a participant in, the robbery and murder of Isadore Rozeman".

If prosecution had been privy to the information initially, the motion said, "Ford might not even have been arrested or indicted for this offence".

Caddo Parish Assistant District Attorney Catherine Estopinal declined yesterday to elaborate on what she termed "a recent development" that prompted prosecutors to reverse course.

"I can't go into it," she said.