The Cambridge police officer who fatally shot 20-year-old Sayed Faisal earlier this year will not be prosecuted, Middlesex District Attorney Marian Ryan announced Thursday.

He was shot and killed on Jan. 4 by Officer Liam McMahon, whose name had not previously been disclosed. McMahon joined the police department in 2015.

“At the moment that Officer McMahon fired his weapon, a reasonable law enforcement officer in the same position would reasonably believe that he, along with his fellow officers and others, were in imminent danger of being seriously injured or killed,” the report reads. “Therefore, the Court finds that the fatal shooting of Sayed Faisal on January 4, 2023, was justified and does not constitute a criminal act.”

The independent investigation into Faisal’s shooting began in February. The 12-page report, released Thursday, is based on more than two dozen interviews and 53 pieces of evidence.

A Cambridge resident called 911 when they saw Faisal jump out of an apartment window and cut himself with a large knife, per police. According to the report, he ran through several streets in the Cambridgeport neighborhood with the knife to his throat. Officers followed Faisal into a backyard, where they positioned themselves to keep him from leaving the backyard, according to the report.

Another officer, Robert Colbert, first shot Faisal with a less-than-lethal “sponge” round as Faisal approached him. Faisal then approached McMahon with the knife held out in front of him, McMahon yelled at Faisal to drop the knife, then McMahon shot him six times when Faisal got within 5 to 10 feet of him. The report noted that at the moment McMahon fired, he was in an enclosed yard with a fence behind him.

Faisal was taken to Massachusetts General Hospital, where he died of blood loss. The autopsy concluded that the six gunshot wounds were the cause of death.

Faisal’s family disagrees with the findings included in the report, asserting that McMahon was farther away from Faisal at the time of the shooting.

“The reports and photographs submitted only after testimony concluded directly contradict the police account of the shooting,” Marsha Kazarosian, the family’s lawyer, said in an emailed statement Friday. “Sayed’s family is considering other legal remedies to ensure there is justice for Sayed and accountability of the officers and the City.”

His death spurred outrage in the community, with a series of protests in Cambridge earlier this year calling for the release of information about the shooting and for the Cambridge Police Department to update some of its practices.

The month after Faisal’s death, the Cambridge Police Department pledged to implement body cameras for police and look at alternative responses to 911 calls.

In a statement released Friday, Cambridge City Manager Yi-An Huang wrote that the response to people in mental health distress who are wielding a dangerous weapon needs to improve.

“We are making significant progress on the commitments we made in February, including implementing body worn cameras, improving less lethal options, and rolling out a procedural justice dashboard,” Huang wrote. “We have hired 11 people in our Community Safety Department including two social work clinicians and six crisis responders who are receiving extensive training and will provide an alternate response to emergency calls starting in 2024. And we have worked with the Police Executive Research Forum, an independent consultant, to develop a new policy for releasing information to the community faster in the aftermath of a fatal police shooting.”

Huang wrote that it has been a “heavy” 10 months for the city and that his heart continues to break for Faisal’s family, friends, and others in the community who were impacted. That’s a sentiment Ryan also shared.

“My condolences have been and remain with the family of Sayed Arif Faisal and those who continue to feel the profound pain of his passing,” Ryan wrote in a press release Thursday.

Fatema Ahmad, executive director of the Boston-area Muslim Justice League, said the conclusion of the inquest was exactly what she expected it to be.

“We knew going into this that this inquest process and these systems are really unlikely to deliver any kind of justice in these situations,” Ahmad said. “And that’s not just here in Massachusetts, that’s nationally the case. And it doesn’t change the fact that community members know that this was unjust and that [Faisal] should still be alive today.

She stressed that the release of the inquest was just one piece of the process, and that she wants to see more done by Cambridge to invest in community care and move away from policing.

“We have to do both. It’s an investment in care and other forms of meeting community needs while we also are, you know, divesting or taking power from law enforcement,” she said.

The Middlesex district attorney’s office shared the report with Cambridge Police “for whatever internal review and action the Department may deem appropriate,” according to the office.

Ryan declined to comment beyond the press release.

In a statement, Cambridge Police commissioner Christine Elow said she mourned Faisal’s death.

“There is no doubt that this is a tragedy for our entire community," Elow said. "My heart goes out to Faisal’s family and everyone who has been impacted."

Elow's statement also said the department remains deeply committed to thorough introspection, learning and growth as an organization.

Kenneth Anderson, the attorney for McMahon in the inquest process, told GBH News the result was a relief but not unexpected.

“It’s been a horrific experience for [McMahon] to go through,” he said. “And it’s not just him, it’s all the officers who were there. I mean, nobody wanted this ending. But unfortunately, they didn’t make that choice.”

Anderson said McMahon is planning to return to active duty.