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Prosecutors won’t retry suspect in Boston detective’s 1993 slaying

Sean Ellis (above) won’t be tried for a fourth time in the killing of Boston police Detective John J. Mulligan.
Sean Ellis (above) won’t be tried for a fourth time in the killing of Boston police Detective John J. Mulligan.Craig F. Walker/Globe Staff/File 2016

The 25-year pursuit of a man authorities allege was responsible for the 1993 killing of Boston police Detective John J. Mulligan ended Monday, when Suffolk prosecutors said they would not retry Sean K. Ellis for the murder.

Suffolk District Attorney John Pappas said the decision, while “incredibly difficult,” was the right one. Pappas said he wanted to make clear that authorities were not exonerating Ellis but had concluded they could not win a conviction.

“The nature of the evidence has not changed in 25 years, but the strength of it has declined with time,” Pappas said. “Moreover, the involvement of three corrupt police detectives to varying degrees in the investigation has further compromised our ability to put the best possible case before a jury.”

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Boston Police Commissioner William Gross said he continues to believe that Ellis “is culpable” for Mulligan’s murder.

“But it’s been over 25 years and this new case would be based on the strength of the evidence,” he said. “The decision was based on that, not innocence at all.”

Ellis is “very relieved and gratified” by prosecutors’ decision to drop the case, said his lawyer, Rosemary Scapicchio, adding that “the manner in which they did it, and smeared his name again, was infuriating.”

Scapicchio said investigators have not showed interest in pursuing other suspects or following up on evidence or leads that could suggest someone else killed Mulligan, who was shot five times in the face with a .25-caliber pistol while working a paid detail outside a Roslindale drug store.

They are dropping the case because they cannot prove it, she said, “and they can’t prove it because he didn’t do it.”

Ellis was convicted in 1995 of first-degree murder in the death of Mulligan. His co-defendant, Terry L. Patterson, was convicted of first-degree murder in a separate trial. But both convictions were overturned when one judge found corrupt detectives played an outsized role in the Mulligan investigation, and another judge ruled fingerprint evidence used against Patterson was unreliable.

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Patterson pleaded guilty to a reduced charge of manslaughter and was released from prison in 2007.

Ellis remained imprisoned for 22 years, 7 months, and 29 days until regaining his freedom in 2015 after Superior Court Judge Carol Ball ruled “justice may not have been done’’ because of “corruption within the investigation of Mulligan’s homicide itself” by Boston police.

“As we all well know detectives Kenneth Acerra, Walter Robinson, and John Brazil disgraced themselves and tarnished their badges in a wide variety of conduct unrelated to this case, the extent of which was unknown to prosecutors or defense council in 1995,” Pappas said. “Perhaps more than any other factor, their shameful conduct presents a major challenge to putting a successful case to a new jury.”

Acerra and Robinson pleaded guilty to federal corruption charges in the late 1990s.

Brazil was immunized from prosecution in return for his testimony.

The state’s highest court upheld Ball’s ruling in 2016.

Pappas said officials met with Mulligan’s family last week and “with incredible dignity and grace [they] understood the outcome and the decision we arrived at.”

Richard Mulligan said he “respects the judgment” of prosecutors and Boston police.

“It’s been 25 years,’’ said Mulligan’s brother, Richard, who has been a mainstay at court hearings in the case over the decades. “It was a difficult experience 25 years ago and it’s going to be a difficult experience now. No matter what happens, it doesn’t bring him back. He’s dead.”

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He remains convinced Ellis murdered his brother.

“I think that Ellis hit the lottery. He’s a free man,” he said. “Sean Ellis is the person who did it; he pulled the trigger five times.”

Dan Conley, former Suffolk district attorney who left the office in September, said he supported the decision.

“It was the direction I was moving toward,” he said, because a conviction at trial was “highly unlikely.”

Ellis was 19 when he was arrested for Mulligan’s murder, which authorities alleged was committed so he and Patterson could steal his department-issued pistol.


Mark Arsenault can be reached at mark.arsenault@globe.com. Follow him on Twitter @bostonglobemark. John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.