In the pre-dawn darkness of 1995, Officer Michael Cox became a crime victim — at the hands of fellow Boston police officers

Boston Police Officer Michael A. Cox talked to the media about the night he was attacked and beaten by other police officers in 1995 on Oct. 29, 1998DOMINIC CHAVEZ/globe staff/file

Early on a Wednesday morning, amid one of the most violent criminal periods in Boston’s long history, Boston Police Officer Michael A. Cox ran into a dead-end Mattapan street after a murder suspect. Moments later, Cox, dressed in plainclothes, was pummeled by fellow officers who mistook him for the wanted man and beat him unconscious.

“I felt a real sharp blow on the back of my head. . . . It felt like a metal pipe, or, you know, very hard object,” Cox, who is Black, testified during a federal trial in 1990s. “I started to look up and the person kicked me in my face, in my mouth in particular. He was a white male and he had on what looked like a uniform.”

“I was hit many, many times, it seemed like all at once, in different parts of my body . . . my head, my back and my face. Mostly my upper trunk. But it seemed like there were several people hitting me all at once,” Cox testified after the brutal attack, according to earlier Globe coverage.

It would take Cox, then a veteran plainclothes officer, six months to recover from the beating. And his fellow police officers would spend years trying to cover up what happened.

Today, officers in some departments are required to report crimes committed by colleagues. But no such standard existed on Jan. 25, 1995, when Cox was attacked.

There were two unwritten rules among Boston police officers back then: Punish any officer who pursued a complaint against a colleague, a stance that was ruthlessly enforced against Cox and his family. Following the incident, Cox’s tires were slashed and his family received numerous hang-up telephone calls at night, the Globe reported. Second was the perpetuation of a “code of silence” among colleagues. It was rare for anyone to talk to department investigators about who got hurt and why.

In Cox’s case, he spent years fighting his own department in state and federal courts, demanding to know who harmed him, and insisting that those who attacked him should not continue to represent the city with a gun and a badge.

The Globe Spotlight Team reported in 1997 that of the nearly two dozen officers required to file reports about what they saw or heard that night, not one said they witnessed an attack on Cox, or even saw him injured.

Boston Police Commissioner Paul F. Evans eventually disciplined four officers — James Burgio, David C. Williams, Ian A. Daley, and then-Sergeant Robert A. Dwan. But that did not take place until 1999, four years after the attack. None of the officers ever faced criminal charges.

During a civil rights jury trial in US District Court, Williams and Burgio were found liable for violating Cox’s rights by using excessive force to subdue him, and for their indifference to Cox’s medical needs. Burgio also was found liable for assault and battery on Cox, but not responsible for intentional infliction of emotional distress.

Daley was found liable for ignoring Cox’s medical needs, but not liable for the beating and allegedly ignoring the assault, the Globe has reported.

The only police officer at the scene that morning who faced criminal charges was Kenneth M. Conley, who also rushed down the dead end known as Woodruff Way at the same time as Cox. Conley, who always insisted he did not see the attack on Cox, was prosecuted in federal court for perjury in 1998. He was convicted and sentenced. But he was allowed to remain free, pending appeals. His conviction was overturned by two different federal judges.

Conley, who was acquitted by the jury in a civil trial, later rejoined the department and is now a sergeant detective, according to city records.

Stephen A. Roach, one of the Boston attorneys who represented Cox during his years of litigation against the city, the department, and the officers who beat him, applauded Wu’s decision.

“I think the city of Boston has finally made a very, very intelligent decision as to who should be the commissioner of the city of Boston Police Department,” he said in a phone interview Wednesday. “My feeling is if this hadn’t happened to him originally, I think he probably would have been a commissioner before this. You can quote me on that.”

The morning that Cox was attacked began with a murder inside a Grove Hall restaurant that led to erroneous reports that the victim was a police officer.

Four suspects drove off in a gold Lexus pursued by several agencies, among them Boston police — including then-gang unit member Michael Cox and his partner — at speeds reaching 90 miles an hour, the Globe reported.

The Lexus finally came to a stop on dead-end Woodruff Way in Mattapan and the suspects jumped out of the car. Cox ran down the dead-end street and was climbing a fence after one of those four men when he was pulled back and pushed to the ground, then battered to the point of unconsciousness.

Rushed to a Boston hospital that morning, Cox was treated for egg-sized contusions on his head, multiple lacerations on his face and lips, a concussion, and kidney damage, the Globe reported.

None of the reports prepared by officers for the homicide investigation made any mention of the beating of Cox, or the fact that a fellow officer was injured seriously enough to warrant hospitalization, the Globe reported.

“This is a homecoming for me… [and] a fairly emotional moment,” Cox said Wednesday. “It was a tough time but the reality is I love public service, and part of my healing process was [asking], what do I want to do with my life? And I thought, you know what, I’m not going anywhere.... I don’t know how to fix this, but I’m gonna stick around and see if I can figure it out, and that’s what I did in so many ways.”