A Boston Police officer who fatally shot a Dorchester man last week was arrested and charged with manslaughter on Thursday.

Officer Nicholas O’Malley, 33, of Randolph, pleaded not guilty Thursday afternoon in Roxbury Municipal Court. He was released on personal recognizance but made to surrender his firearms.

It’s believed to be the first time in decades that a Boston police officer has been charged with manslaughter for an on-duty shooting.

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Police say O’Malley shot and and killed 39-year-old Stephenson King on March 11 as King was fleeing police in a car he had allegedly stolen in an unarmed carjacking.

O’Malley and another Boston Police officer found King behind the wheel of the parked vehicle in Roxbury at about 9:43 p.m., according to a police report. The officers yelled at King to show his hands and shut off the engine. The report says King showed his hands, but did not shut off the vehicle or unlock the doors.

Standing outside the driver’s window, the report says O’Malley shouted, “Bro, I’m gonna f***ing shoot you,” before King put the car in reverse, backing into the police cruiser behind him. He then drove the car forward and reverse in an attempt to escape, and O’Malley drew his gun.

“Officer O’Malley fired through the driver’s side of the car, striking Mr King three times and killing him just as he drove away,” Suffolk County District Attorney Kevin Hayden said at a press briefing following the arraignment. “The evidence demonstrates that Officer O’Malley fired at a moving vehicle, an action prohibited, except in limited circumstances not present here, in violation of Massachusetts law and clear BPD procedures.”

Read the report here.

The report says O’Malley claimed King “tried to run us over,” and that he fired his weapon because he thought his fellow officer was going to be crushed by King’s vehicle.

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Hayden said body camera footage and interviews at the scene showed that wasn’t true.

“While evidence demonstrated that Mr. King was not complying with the commands of the officers, at no time in his attempt to flee did Mr. King drive at the officers, nor were either officer in the path of Mr. King’s vehicle when Officer O’Malley opened fire,” Hayden said.

In court, the prosecutor said the other officer was at greater risk of being hit by the bullets fired by O’Malley than he was of being hit by the car.

The police report notes that while the law allows police officers to use deadly force when reasonably necessary, it says that officers “shall not discharge any firearm into or at a fleeing motor vehicle” unless it is necessary to “prevent imminent harm to a person” and the gunfire is proportionate to the threat.

Hayden said the body camera footage will not be released to the public.

O’Malley’s attorney, Ken Anderson, described his client as an officer with an unblemished record who should not have been arrested for his actions. Anderson said the body camera footage only tells part of the story.

“That body-worn camera does not have human adrenaline. That body-worn camera’s not worried about not seeing somebody’s hands. That body-worn camera isn’t worried about going home safe at night,” Anderson said to reporters after the arraignment. “My client’s perception is what matters here, and he stands by his actions. I think at the end of this case, he’s going to walk away as an innocent man.”

In the courtroom, Anderson described O’Malley as a lifelong Massachusetts resident and a graduate of Westfield State University who is married with two children, a 3-year old and a 6-month old. He objected to the fact that O’Malley was arrested in his home, rather than being allowed to turn himself in, and he suggested that the move was an “election year” ploy by Hayden, who is up for reelection.

“They go and arrest somebody off the street who clearly is not a flight risk. They ask for $25,000 cash bail for someone who’s lived every day of his life in Massachusetts, married… two young kids, not a flight risk. And they grab him off the street, they arrest him, they book him to embarrass him, to put this show on for all of you,” Anderson said to the gathered reporters.

Hayden pushed back on the suggestion, which Anderson had also made earlier in the courtroom.

“This has nothing to do with an election year,” Hayden said. “That has nothing do with public opinion. Has nothing to with politics. This has to do us following the facts and the applicable law and the circumstances. That’s what we’re always guided by. We’re never influenced by that. Not in any other case and not in this one.”

Around 40 uniformed Boston police officers showed up to the Roxbury courthouse for O’Malley’s arraignment, and lined up behind their union president, Larry Calderone of the Boston Police Patrolmen’s Association, as he spoke with reporters.

More than a dozen officers line up in solidarity on the sidewalk.
About 40 Boston police officers lined up in solidarity with Nicholas O’Malley, who pleaded not guilty to manslaughter charges Thursday.
Arthur Mansavage GBH News

“These men and women come to work every day to keep Boston the safest city in the country. The very freedoms that we all enjoy, you and us together, are because of these men or women behind me,” Calderone said. “And in a split second, they have to make a determination on what to do.”

Calderone pointed to comments that Anderson had made in court, that at the time of the shooting, King was out on bail on four pending felony cases.

“Now, I’m not there to pass blame to the individual,” Calderone said. “It is a complete tragedy that we’re here today even talking about this. It really is. But we have an individual that’s no stranger to the criminal justice system.”

And he said that as officers are forced to make split-second decisions, they need to rely on the compliance of the public.

“When a law enforcement officer comes on scene and they’re giving you verbal commands and they’ve given you instructions, it’s a two-way street. Compliance is a must,” he said. “No officer ever wants to take a life, ever wants to discharge their firearm. But we carry that piece of equipment to keep you and your family safe. And we do a very good damn job at it. The facts show it. That’s why we’re the safest city in America. So we’re here very strongly to tell you that we back our officer.”

In statement, Boston Police Commissioner Michael Cox
said it was “a difficult day for the Department and our City.”

“We remain committed to our mission of building trust while reducing crime and fear of crime with those we serve. As this case is now in the criminal justice system, we will not comment on the facts at this time,” Cox said. “We rely on the integrity of the criminal justice system in what we do every day, and this case will be no different.”

Meanwhile, the Massachusetts Peace Officer Standards and Training Commission, which oversees police licensure, announced Thursday it had suspended O’Malley.

The manslaughter case will now be brought before a grand jury. O’Malley’s next court date is May 21.

Updated: March 19, 2026
This story was updated to include additional statements from O'Malley's attorney, the BPPA and Commissioner Cox.