After spending more than 21 years in prison following his conviction on charges of killing a Boston police detective in 1993, a former city man was granted a new trial — his fourth — in the controversial case on Tuesday, his lawyer said.
Suffolk Superior Court Judge Carol S. Ball allowed Sean Ellis’s motion for a new trial in the slaying of Detective John J. Mulligan, defense lawyer Rosemary C. Scapicchio said.
Boston police declined to comment. The Boston Police Detectives Society union also could not be reached for comment.
Jake Wark, a spokesman for Suffolk District Attorney Daniel F. Conley, said in a statement that Scapicchio told prosecutors late Tuesday that Ellis had been granted another trial.
“We have not yet received word from the court or a copy of the judge’s findings, but we strongly disagree with the decision to vacate the jury’s verdict and we’re reviewing all of our appellate options,” Wark said.
Scapicchio plans to seek bail for Ellis, 40, and insisted that he is incarcerated “for a crime that he didn’t commit.”
Mulligan’s family could not be reached for comment late Tuesday.
Scapicchio said Ball allowed Ellis’s bid for a new trial in part because authorities withheld information from his trial counsel, including the alleged involvement of Mulligan and another detective in an armed robbery more than a year before Mulligan’s death.
The 52-year-old Boston detective was shot in the face with a .25-caliber pistol while working a uniformed, paid detail at a Walgreens pharmacy on American Legion Highway in Roslindale in the early morning of Sept. 26, 1993.
Mulligan was sitting in his rented sport utility vehicle in front of the store, apparently sleeping, when he was killed. His 9mm Glock service pistol was stolen; prosecutors said Ellis had wanted the gun as a trophy.
Despite evidence that Ellis at some point had the murder weapon and Mulligan’s service pistol, his first two trials ended in hung juries. Ellis was convicted of first-degree murder in the third trial.
In seeking a new trial, Scapicchio argued in 2014 that recently discovered evidence linked Mulligan to a conspiracy in which Boston officers allegedly robbed drug dealers. This connection, she said at the time, revealed a new motive for the slaying and perhaps a different killer.
Mulligan’s brother, Richard, previously told the Globe that “the jury heard all the evidence. It’s compelling evidence that convicted him. . . . They placed him at Walgreens; they placed him in the parking lot.”
Richard Mulligan added, “These guys think that the general public are a bunch of fools.”
Ellis, who was 19 at the time of the killing, said he had been shopping for diapers that night after receiving a ride from Terry Patterson, a friend. Ellis told authorities he saw Mulligan alive in his sport utility vehicle, which had been parked in the fire lane just outside the store.
Patterson was convicted separately but later granted a new trial in 2000. He pleaded guilty to manslaughter and was released from prison in 2007.
During their trials, Ellis and Patterson each accused the other of the killing.
A key prosecution witness against Ellis was Rosa Sanchez, a teenager whose aunt had dated Kenneth Acerra, a detective and a friend of Mulligan’s who was involved in the investigation.
At first, Sanchez identified someone other than Ellis as the man she saw outside the drug store. But after a conversation with Acerra and his partner, Walter Robinson, she chose Ellis from an array of photographs.
At trial, Sanchez testified that she saw Ellis crouching next to Mulligan’s vehicle before the officer was killed.
Acerra and Robinson pleaded guilty in 1998 to federal corruption charges and were both released in 2001. Attempts to reach Acerra, Robinson, and Sanchez for comment were unsuccessful on Tuesday.
Scapicchio said Ellis wept when she visited him Tuesday night at MCI-Norfolk, where he is serving a life sentence, and informed him that he had been granted a new trial.
“We’re just so relieved and so happy at the chance to get a fair trial,” she said.
John R. Ellement of the Globe Staff and Globe Correspondents M.G. Lee and Zolan Kanno-Youngs contributed to this report.