For the first time in years, Michael J. Sullivan can now walk as a free man, without a prison guard or an ankle bracelet monitoring his every move or a three-decade-old murder charge hovering over him.
“I feel like a new man,’’ he said Saturday, one day after Middlesex District Attorney Marian T. Ryan dismissed charges against him in the 1986 murder of 54-year-old Wilfred McGrath in an East Cambridge apartment.
Sullivan had been convicted of first-degree murder in 1987. But a Middlesex Superior Court judge in 2012 ordered a new trial for Sullivan, after advanced DNA testing cast doubt on his guilt.
Sullivan was released from prison on an ankle bracelet nearly seven years ago, as he awaited a new trial.
The wait ended Friday, when Middlesex prosecutors determined too much time had passed to successfully retry Sullivan.
“Given that nearly 33 years [have] passed since the murder, there has understandably been a diminishment of the health and memory of potential witnesses,’’ Ryan’s statement said. “Additionally, a number of the witnesses who testified at trial have died.”
Court documents show that at least eight of the 13 witnesses who testified at trial are deceased and that DNA testing performed years after McGrath’s death produced results that “impacted certain forensic testimony by eliminating an item of clothing as evidence linking the defendant to the crime,’’ according to court documents.
The state could not meet its burden to prove the elements of the offense beyond a reasonable doubt, Ryan said in the statement.
The decision ended a yearslong fight for Sullivan, now 58, and his attorneys to clear him in the murder of McGrath, who was lured to an East Cambridge apartment and robbed of money, jewelry, and cocaine, before being left for dead behind an abandoned supermarket.
The decision also felt like vindication to Sullivan, who was 25 when he was sentenced to a life in prison for the crime. He has denied any involvement in the murder.
“I had nothing to do with it and the DNA proves it,’’ he said. “I never met that man in my life.”
Sullivan and his attorneys have been arguing that Sullivan was wrongfully convicted in the case since 1991.
Arthur L. Kelly, the lead trial attorney for Sullivan for the past four and a half years, said he has been arguing that DNA and other flaws made “the case untriable.”
“I feel wonderful about [the dismissal] because I wouldn’t want to envision this man who spent the past 27 years in prison for a crime he did not commit to face the jeopardy of another trial,” Kelly said.
Sullivan’s attorneys argued that DNA would support his claim that he was not involved in the murder. The judge agreed, but prosecutors appealed to the state Supreme Judicial Court. In 2014, the court upheld the decision to grant a new trial.
The high court agreed that new testing showed that there was no blood, invisible or otherwise, on the cuffs of the jacket that the prosecution’s star witness testified Sullivan wore when McGrath was beaten to death, the court said.
That star witness, Gary Grace, had murder charges dropped in return for testifying against Sullivan and served about six years in prison, the Globe previously reported.
A defense witness, Emil Petrla, testified that he and Grace — not Sullivan — killed McGrath, the paper said. Petrla’s testimony led to a second-degree murder sentence, the Globe reported.
The only independent evidence that would help jurors choose who was telling the truth was the jacket, the SJC said.
Sullivan said Grace had been his next-door neighbor and did not like Sullivan.
“He was the prosecution’s star witness,’’ said Sullivan, adding that he did not know why Grace had singled him out.
Sullivan, who now lives in his sister’s apartment in Lowell, described life in prison as cycling through Walpole, Old Colony, and Gardner correctional facilities, dabbling in painting and laboring in the laundry. He said was unable to attend the wake and funeral of his mother, who died in 1995, and three of his siblings.
His return to civilian life has not been smooth, however. Sullivan, who is not employed, said he has had odd and ends jobs since 2013.
He had a brief return to jail in 2015 on drug charges in Billerica.
Dana Curhan, a lawyer who represented Sullivan, said Sullivan had unknowingly given a ride to a man who was involved in a drug transaction. The charges against him in that case were ultimately dismissed, Curhan said.
In the case, Sullivan said he had gone to get a haircut and afterward his barber had asked him for a ride to the barber’s family’s house.
But “we never made it out of the parking lot,’’ which Sullivan said was swarmed by police.
“I had no drugs on me — nothing,’’ he added. “I didn’t know the kid that well.”
The case was dismissed, he added.
The Middlesex district attorney’s office could not immediately respond to questions about the Billerica case Saturday.
On Friday, Sullivan returned to a courtroom with his eyes focused on his future. He wore a new gray suit and green tie his sister Donna bought him when they got the good news that the charges had been dropped.
“It’s unbelievable,’’ he said. “I can go anywhere now. It’s a really big thing.”Correspondent Jeremy Fox and John R. Ellement of the Globe Staff contributed to this report. Meghan Irons can be reached at firstname.lastname@example.org. Follow her on Twitter @MeghanIrons.