A video shot by a civilian and posted to Facebook begins with the officer, who is wearing a Red Sox jersey over his department pants, crouched on top of a man who is lying on the ground. The officer’s knee is on the man’s back, and he appears to be holding him down with his hands.

Police officials confirmed Wednesday that an Internal Affairs review of the incident, which occurred the day before, is underway, but said the officer, a 20-year veteran of the force, has not been disciplined in any way. Police did not name the officer.

Boston police have launched an internal investigation after video surfaced of an off-duty officer roughing up a civilian in the Back Bay, which began when the man was crossing a street and struck the officer’s car window with his umbrella as the vehicle turned onto the road.


“You know what I’m doing,” the officer tells the man, who he had chased down the street. “Why were you running?”

“Because you cut me off,” the man says.

“You [had] the don’t walk sign,” the officer says, jabbing his index finger toward the man’s face. “Get up.”

The officer then pulls the man up by his shirt collar and walks him several blocks back to the scene of their initial encounter at Arlington and Boylston streets.

During the walk, the officer pushes the man forward while maintaining a grip on his shirt, telling him, “You’re under arrest right now.”

The man who shot the video, Stephen Harlowe, 47, said that the incident occurred at 5:20 p.m. on Tuesday.

He said that before he started filming, the officer had jumped on the man and slammed his head on the ground.

“He was terrified of the guy,” Harlowe said of the man being detained.


At one point during the walk up the block, the man says to Harlowe: “He cut me off at the corner. I tapped his [car’s] glass with my umbrella.”

Once they make it back to the intersection, the officer puts the man against the side of his personal vehicle, and Harlowe asks the officer if he has a badge. He also informs the officer he is being filmed.

“No, I have an ID, though,” the officer responds, later adding when Harlowe accuses him of shoving the man’s head in the ground, “You can say that I did whatever I did, you know?”

While the officer is calling 911 on his cellphone, a woman approaches and tells him that she works with the man being detained and says, “This is a good man.” The officer, meanwhile, tells the dispatcher, “He cracked my car window with his phone.”

Harlowe later pans over to the window the officer says was cracked, and a vertical blemish of some kind is visible.

Boston police Officer James Kenneally, a department spokesman, said the person the officer detained, identified only as a 54-year-old man, had not been charged with any crimes as of Wednesday.

In an official department report on the incident, police wrote that the officer said he had a green light as he turned right onto Arlington Street in his personal vehicle, when the man “struck his vehicle’s right rear driver’s side window as he was crossing illegally against the green light.”

The report continued: “When asked, [the man] confirmed that while crossing the intersection . . . [the officer] did have a green signal, but he was upset that [the officer] did not allow him to cross ahead of him and struck the window with his umbrella. A large vertical scratch was initially visible but was able to be wiped from the surface of the glass.”


The video does not show the moment when the man was crossing the street.

Near the conclusion of the video, as the officer holds the man against his car and waits for police to arrive, he also gets into a dispute with Harlowe.

“You didn’t yield to a pedestrian?” Harlowe asks.

“I have the right of way,” the officer responds.

“It doesn’t matter,” Harlowe says. “In the state of Massachusetts, if he’s in a crosswalk . . . ”

“You’re wrong,” the officer answers.

“I’ll call the chief,” Harlowe responds.

“Call whoever you want, and do whatever you want,” the officer says.

Boston police and state troopers later arrive and speak with the parties, and the video soon ends.

Christopher Ott, spokesman for the American Civil Liberties Union of Massachusetts, said that the case illustrates why officers should be outfitted with body cameras. The officer in question, however, was off duty.

With cameras, Ott said, “neither members of the public nor the BPD would have to rely on bystander videos to understand situations like this, and to protect people on both sides of the badge,” Ott said.

Travis Andersen can be reached at travis.andersen@globe.com. Martha Schick can be reached at martha.schick@globe.com.