Terrence Sterling, 31, of Fort Washington, Md., was fatally shot by a District police officer after he crashed the motorcycle he was riding into a police cruiser during a traffic stop on Sept. 11, 2016. (Family Photo)

A review board has concluded that a D.C. police officer should be fired for shooting an unarmed motorcyclist last year in Northwest Washington, saying he violated department policies.

Officer Brian Trainer is appealing those findings, police said, which could lead to a public inquiry early next year that resembles a trial but is adjudicated by a panel of senior police leaders.

Federal prosecutors in the District already have decided not to pursue criminal charges against Trainer in the shooting of Terrence Sterling, 31, announcing in August that there was not enough evidence to show that the officer used “unreasonable force.” Still, officials including Mayor Muriel E. Bowser (D) did call on Trainer to resign, and Sterling’s family and supporters continued to question the incident.

“Our family has continued to pray that the truth will come to light,” Sterling’s father, Isaac Sterling, said in a statement. “We are encouraged by the Use of Force Review Board’s finding that Terrence’s killing was unjustified, which brings us one step closer to finding justice for Terrence’s death.”

A candle burns as protesters shut down an intersection following a candlelight vigil and rally for Terrence Sterling on Oct. 3, 2016 in Washington. (Ricky Carioti/The Washington Post)

Although Sterling’s Sept. 11, 2016, death never gained the national attention of some other police shootings of unarmed suspects, marches and vigils were held in the weeks and months afterward.

Police said Sterling was shot when he intentionally ran his motorcycle into the door of a marked police cruiser as Trainer was getting out to stop the bike.

Sterling had been driving erratically that night, running red lights and reaching speeds of more than 100 mph, prosecutors had concluded. But some have questioned whether Trainer and another officer who sought to arrest Sterling acted appropriately, including pulling into an intersection to block the motorcyclist’s path. Trainer also did not activate his body-worn camera until after the shooting, officials have said, violating department policy.

A hearing on the recommendation to fire Trainer, called a trial board, could offer the most detailed account of the shooting, which occurred near the Third Street Tunnel. Such proceedings are typically open to the public.

Neither Trainer nor his attorney could be reached for comment Tuesday. The police union declined to comment beyond noting that Trainer is entitled to due process. The officer, in his later 20s, has been on the force for more than four years.

On Tuesday, D.C. Police Chief Peter Newsham noted that a review such as this is “a very lengthy process. . . . I understand it has taken a very long time. I appreciate the family’s patience. . . . This is a milestone, but we have a little ways to go.” Newsham first discussed the outcome of the shooting review during an appearance on a FOX 5 morning news show.

Authorities would not discuss what specific procedures Trainer is alleged to have violated. The police began their administrative review in August after prosecutors decided not to press criminal charges.

Three officials with knowledge of the case said the officer who was driving the car previously was suspended for 20 days for a variety of administrative infractions, including engaging in an unauthorized pursuit.

District officials treated the shooting of Sterling differently than in other cases. The department does not generally identify officers involved in shootings, but Bowser ordered Trainer’s name be made public to demonstrate transparency and to encourage witnesses to come forward.

On Tuesday, the mayor said she was pleased with the outcome of the internal review. “I said early on that I thought it best the officer separate from the department,” she said in a news conference to announce a decline in robberies.

D.C. Council member David Grosso (I-At Large) also said he wants the officer to resign.

“This is the right course of action,” he said. “I hope that it can give those who loved Mr. Sterling some sense of justice.”

Sterling’s family has filed a civil suit that is pending.

The incident began about 4:20 a.m., when officers got a call about a motorcycle being driven erratically in the Adams Morgan area. An autopsy found that Sterling’s blood alcohol level was twice the legal limit, and he tested positive for marijuana.

Later, Trainer and his partner saw the motorcycle near Third and M streets NW and pulled into an intersection ahead of the biker. Police have not detailed what happened between Adams Morgan and the tunnel.

Prosecutors determined that Trainer had unholstered his gun, keeping it pointed down and toward his body, as he began to get out of the car. Sterling drove toward the cruiser, and “the impact caused by the advancing motorcycle caused a dent in the cruiser’s open door and a bruise to the officer’s knee.”

Two witnesses interviewed by The Washington Post said that the crash did not appear deliberate and that they thought that Sterling was trying to move around the police car.

Authorities said that Trainer was getting out of the cruiser when Sterling “revved his motorcycle and then accelerated” toward the car. Prosecutors said Trainer felt the motorcycle hit the door and reacted by firing two rounds at Sterling through the car’s front window.

Keith L. Alexander and Clarence Williams contributed to this report.