Sean Ellis is officially a free man, after state prosecutors announced Monday they would not pursue a fourth trial against him – ending the 25-year legal case that involved two hung juries, an overturned conviction, and allegations of police corruption.

“It’s done,” Ellis told Jim Braude during an interview Tuesday. “I don’t have to go to sleep and wake up, worrying about whether or not I’m going to be sent back to prison.”

Ellis had served 22 years in prison after being found guilty of first-degree murder in the 1993 death of Boston Police Detective John Mulligan. That conviction was overturned in 2015 by a judge who ruled in the defense’s favor that Ellis had not received a fair trial.

“When this investigation first started, I believe that [Detectives] Acerra, Robinson and Brazil were desperate to shut down the investigation, because if people really knew what Mulligan was up to, their own corruption would have been exposed,” said Ellis’ defense attorney, Rosemary Scapicchio.

Those three detectives were implicated after Mulligan’s death in federal extortion charges that involved falsifying warrants and robbing accused drug dealers. Acerra and Robinson pleaded guilty to the charges in 1998, while Brazil was given immunity for testifying. Suffolk District Attorney John Pappas described those charges Monday as “unrelated” to Mulligan’s death — but the 2015 ruling by Judge Carol Ball said there was evidence to back up the defense’s argument connecting the police officers’ misdeeds and their rush to end the murder investigation by pinning it on Ellis.

“It was reported to [police] that Mulligan and Robinson had robbed a drug dealer at gun point, and none of that information was turned over to Sean,” said Ellis’ defense attorney Jillise McDonough, speaking of then-commissioner William Bratton and his successor, Paul Evans.

“There were countless tips that were called into the tip line that implicated people — none of that was turned over to Sean or his counsel,” she added. “One of the tips was assigned to Acerra to investigate, and nothing ever came of it.”

Although Ellis was freed on bail in 2015, he still faced a potential fourth trial until the District Attorney’s announcement this week. His first two trials ended in a hung jury, and he was convicted on his third.

During a press conference, the Suffolk District Attorney's Office and Boston Police Commissioner William Gross emphasized that their decision to decline a fourth trial did not amount to a declaration of innocence.

“If evidence is based is truth, no matter how much time elapses, then it’s going to stand up,” Ellis responded. “So the fact that [Gross] is acknowledging that 25 years later, there’s a weakness in the evidence — that means it wasn’t strong to begin with.”

Ellis’ defense attorneys also argued on Greater Boston that the timing of Monday’s press conference was politicized.

“I think they were concerned if [District Attorney-elect] Rachael Rollins came in and did the investigation that I think she would have done, she wouldn’t have been praising the Boston Police Department, she wouldn’t have been praising the district attorney who prosecuted the case,” said Scapicchio. “They did it, I think intentionally, three weeks before Rollins took office.”

Asked what he plans to do next, Ellis said that he hopes to go to school — although he noted that even this return to normalcy would require him to first get over a significant financial hurdle.

And in the long run?

“I want to do work to help the epidemic of wrongful convictions,” he said.

This article has been updated with more details.