A Louisiana man who spent nearly three decades on death row has walked free, after prosecutors asked a judge to set aside his first-degree murder conviction and death sentence, citing new evidence in the case that exonerated him.

Glenn Ford, 64, was convicted by an all-white jury for the 1983 robbery and murder of Isadore Rozeman, a 56-year-old Shreveport watchmaker, who was found shot dead behind the counter of his jewellery shop.

Acting on new information that exonerated Ford, a judge in Shreveport ordered him to be released on Tuesday from Louisiana State Penitentiary in Angola, where he has been held on death row since March 1985, according to Reuters news agency.

"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," said Gary Clements and Aaron Novod, lawyers for Ford from the Capital Post Conviction Project of Louisiana.

Multiple appeals

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

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

But in 2000, the Louisiana Supreme Court ordered a hearing over 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 showed that an unidentified informant told prosecutors in 2013 that Jake Robinson admitted to shooting and killing Rozeman.

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

If the 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 on Tuesday to elaborate on what she termed "a recent development" that had prompted prosecutors to reverse course.