A Florida state court panel on Wednesday tossed out the murder conviction of an FBI agent tied to Boston mobster James "Whitey" Bulger.
But government prosecutors are expected to appeal the decision in an effort to keep John J. Connolly Jr. in prison.
The three-judge appellate panel cited a legal error in ruling that Connolly was wrongly convicted of participating in a plot to kill a Florida businessman in 1982 at Bulger's behest. They ordered his release pending an appeal by prosecutors.
Florida officials said they were studying the court's opinion.
Connolly was turned over to state authorities in 2011 to begin a 40-year prison sentence, after serving nine years in federal prison on a separate charge.
Bulger was a fugitive for 16 years and was captured in 2011 while living in hiding in a Santa Monica apartment.
At the time of Bulger's arrest, some 100 former FBI agents and supervisors rallied around the 73-year-old Connolly, hoping to exonerate the disgraced former Boston agent.
"We won," said former agent Richard Baker of Boston, who has led the coalition of ex-FBI agents. "I'm very delighted he's going to finally get to see his kids on every holiday there is. I just have to pray now that somebody doesn't come out of the woodwork and put a wrench in it.... He's not out of jail yet."
Baker said he did not think Florida prosecutors would pursue the case further. "I don't know that the government has any grounds to appeal it," he said. "I'd be surprised if they want to flex their muscles to keep this going."
He said Connolly, despite his age, does push-ups in prison, runs and eats right. "If you want to call it 'eating right' in prison," Baker said.
In a 2-1 vote, the state appellate court panel issued a technical decision that overturned Connolly's conviction -- on second-degree murder with a firearm -- because the four-year statute of limitations on that offense had expired.
The panel further noted that Connolly was not the one who shot businessman John Callahan, president of World Jai Alai, after Connolly allegedly warned Bulger that Callahan might implicate him in another slaying. Callahan's body was found in the trunk of a Cadillac at Miami -International Airport.
"Connolly," wrote Judge Richard J. Suarez, "never carried, displayed, used or threatened to use the murder weapon."
But prosecutors said Connolly often met with Bulger and his Winter Hill gang, including during the time when the plot to kill Callahan was hatched. That relationship was part of the basis for the Oscar-winning film "The Departed," about law enforcement corruption in Boston.