Charges in 1993 murder of a Boston police detective are withdrawn

"Jurors at the time called the case against him overwhelming. But the passage of more than two and a half decades has seriously compromised our ability to prove it again."

Sean Ellis, center. Pat Greenhouse / The Boston Globe, File

A Dorchester man once convicted of murder in the 1993 slaying of a Boston police detective won’t face a fourth trial as the more serious charges against him have been withdrawn, officials announced Monday.

Sean Ellis, who was 19 at the time of Det. John Mulligan’s death, was released from prison in 2015 following a court ruling reversing his convictions of first-degree murder and armed robbery charges, according to The Boston Globe. Ellis had already spent over 22 years behind bars.

While former Suffolk County District Attorney Daniel Conley said in 2016 that he planned to bring Ellis to trial again following a Supreme Judicial Court’s decision that maintained his release, acting District Attorney John Pappas said that won’t be the case in a Monday press conference and subsequent news release.

While he and his team believe evidence still points to Ellis and his co-defendant, Terry Patterson, the decision has to do with the current strength of the evidence. Prosecutors aren’t convinced a new trial would end with a guilty verdict, Pappas said.


“The trial evidence and testimony in 1995 proved Mr. Ellis’ guilt beyond a reasonable doubt. Jurors at the time called the case against him overwhelming,” he said. “But the passage of more than two and a half decades has seriously compromised our ability to prove it again. For this reason, my office will file paperwork today ending the prosecution of Mr. Ellis for first-degree murder and armed robbery.”

Mulligan, 52, was shot five times in the face with a .25-caliber pistol on Sept. 26, 1993, while working a detail at the Walgreens on American Legion Highway. Mulligan was reportedly inside an SUV, sleeping, when the shooting occurred. His service pistol, a 9mm Glock, was stolen.

Pappas noted Monday that Ellis’s two other convictions for “possessing the murder weapon and Det. Mulligan’s service weapon, which was stolen from his body, remain undisturbed.”

The decision to drop the charges also has do with “three corrupt police detectives.” Their involvement in the investigation harms the strength of the prosecution’s case in being able to obtain a new guilty verdict, Pappas said.

“As we all know, Detectives Kenneth Acerra, Walter Robinson, and John Brazil disgraced themselves and tarnished their badges in a wide variety of criminal conduct unrelated to this case — the extent of which was unknown to prosecutors or defense counsel in 1995,” he said.


While prosecutors don’t believe Mulligan was involved with the corruption, Pappas said “it is now inextricably intertwined with the investigation and critical witnesses in the case.”

Pappas stressed that the decision wasn’t based on the idea that Ellis is the victim of a wrongful conviction, noting that he and past Suffolk County district attorneys have “not shied away from exonerating innocent men.”

“But let me be clear: that is not the case here,” he said. “If at any point we had any reason to believe that Mr. Ellis was wrongfully charged or convicted, we would have acted on it immediately.”

Patterson was also convicted of murder, but had it overturned on an appeal — prosecutors settled on a manslaughter charge in 2006 and Patterson was handed 25 to 30 years in prison and ordered to serve 22 years, according to the Globe. However, Patterson was soon released based on time already served and good behavior.

“In the 25 years since Det. Mulligan was murdered in cold blood, not one piece of evidence developed by prosecutors, defense counsel, or anyone else has pointed to anyone but Sean Ellis and Terry Patterson,” Pappas said. “Of all the people in all the world who might have killed John Mulligan, only they were present at the time and place he was killed — by their own admissions, supported by eyewitnesses and physical evidence.”


Watch the full press conference: