“IT’S all good,” Reginald Adams said as he walked free on May 12th, having spent the past 34 years in prison for a murder he didn’t commit. A less forgiving man might have put it differently. New Orleans police and prosecutors should have known they had the wrong guy back in 1979. They recovered the gun used in the murder (of a cop’s wife), and linked it to another pair of criminals who had nothing to do with Mr Adams (pictured).

All the police had against Mr Adams was his confession: one he gave after a marathon interview, during which police allegedly plied him with alcohol and drugs. Mr Adams got almost every detail of the crime wrong, from the calibre of weapon used to the number of shots fired to the sex and hair colour of the victim.

Nonetheless, prosecutors sought the death penalty when they first tried him. And they did not hand over to his defence team the police report tracing the gun’s provenance. Mr Adams’s new lawyers say—and the city’s current district attorney, Leon Cannizzaro, agrees—that detectives knowingly gave false testimony.

As Mr Adams languished in prison, some of his tormentors were caught wandering off the straight and narrow. One prosecutor became a crooked judge and was jailed for it. One of the detectives served five years for vehicular homicide. And Ronald Ulfers, the cop whose wife was murdered, is now serving life in prison for murdering his second wife.

Mr Cannizzaro took only ten days to join the motion by Mr Adams’s lawyers to set aside the guilty verdict. The DA said the misconduct was the worst he has seen. That is saying something. The DA’s office in New Orleans has become notorious for such cases, largely from the three-decade tenure of former DA Harry Connick senior, the father of a well-known singer. Most of the defective cases involve “Brady violations”: failures to give defendants all material that might be exculpatory.

In one case Mr Connick’s men sent John Thompson to death row for a murder he didn’t commit, hiding evidence that would have helped him. Mr Thompson narrowly missed being executed. After his exoneration, he won a $14m judgment against the DA’s office.

Mr Cannizzaro appealed the award, saying it would bankrupt his office. In 2011 the Supreme Court ruled 5-4 in his favour, saying the office should not be held liable for the acts of a “rogue prosecutor”. Dissenting, Justice Ruth Bader Ginsberg wrote that Mr Connick’s office had been “deliberately indifferent” to the Brady rule. The Innocence Project of New Orleans, which represented Mr Adams, counts 31 cases from the Connick era where Brady violations have been proven. Mr Connick has said that his office handled so many cases that a few mistakes were bound to occur.

Not long ago, every pillar of New Orleans’s criminal-justice system was broken. Now the police and the jail are under federal decrees requiring judicial oversight and reforms, and Mr Cannizzaro has done much to improve the DA’s office. But that may be scant comfort for Mr Adams.