Michael A. Cox Sr., a former Boston police officer who rose through the ranks despite once being attacked by fellow officers who mistook him for a criminal, will return as commissioner of the department, Mayor Michelle Wu announced Wednesday.

Cox, who joined the Boston Police Department in 1989, left the city in 2019 to lead the police department in Ann Arbor, Michigan, where he has served as chief for the past three years.

Speaking to reporters, Cox, 57, described his appointment as “a homecoming” and directly addressed how being attacked by fellow Boston police officers three decades ago was an example of “unconstitutional policing” that many people of color and underprivileged folks experience.

In 1995, while working in plain clothes as part of the department’s anti-gang unit, a group of officers mistook Cox for the suspect he was chasing. They beat Cox, then left the scene after realizing his identity. A different group of officers showed up at the scene and called emergency services.

“That was a long time ago, and since that 1995 [incident], I have dedicated my life to making sure that both the Boston Police Department and policing general has grown and learned,” he said.

Cox’s appointment as commissioner marks a turning point in the Boston Police Department, which has gone without permanent leadership for more than a year.

Boston’s immediate past commissioner, Dennis White, was fired last June after serving a monthslong suspension period over domestic violence allegations that resurfaced within days of his appointment.

White is now suing the city and its former acting mayor over his dismissal.

Cox said his first priority when he assumes the post next month will be “letting the department know we have a leader amongst the group again.”

“I’m here to support, develop, include and work with each and every one of them in doing this very difficult job,” he said.

Mayor Wu, who campaigned on a platform of police reform through prioritizing public health and public trust, said she knew Cox would be her pick early in the interview process.

“As soon as we started chatting, I knew he was the one and that our priorities and values aligned, that his love for Boston shines through in discussing every challenge,” she said. “There was such a sense of hope and excitement and joy about what we could get done together, even tackling very complex and quite entrenched systems.”

Ann Arbor Mayor Christopher Taylor praised Cox's deep care for community and dedication to policing in a statement to GBH News.

"Like so many in Ann Arbor, I have enjoyed working with Chief and believe that we are a much better place due to his service,” Taylor said. “I am sorry to see him go, but the pull of home is strong, and I wish him every continued success."

Wu said she selected Cox despite a recent suspension over accusations he created a hostile work environment during investigations into officers voiding parking tickets. A subsequent investigation exonerated Cox.

“There was a very thorough vetting process,” she said, pointing to numerous public documents. “Our investigators also spoke with many, many people in Ann Arbor from all different roles … and I personally spoke with the mayor and town administrator in Ann Arbor, too.

“Those conversations, for me, confirmed what we already knew about Chief Cox from his years in Boston,” Wu continued. “That he is a leader of great integrity, that he takes every step of leadership very seriously and in this case had taken full ownership over any miscomuunications and used that as a learning opportunity.”

Cox noted that the city's investigation concluded there was no evidence of creating a hostile work environment, and said the fear of retaliation his subordinates experienced was based partly on regional cultural differences he only became aware of after moving from his lifelong home in Boston.

“I was new to that location and new to the Midwest, and I really did not understand that people were even receiving it that way,” he said. “I apologize for that, as well as I should, because that certainly was never the intent.”

Cox will assume the role Aug. 15, according to the mayor’s office.