The D.C. police officer who fatally shot an unarmed motorcyclist last year had no reason to pull his gun and was not in danger when he fired, police concluded in an internal investigation that contradicts the officer's account.

The review, obtained by The Washington Post, showed that Officer Brian Trainer and his partner, Officer Jordan Palmer, violated department policies early on Sept. 11, 2016, as they pursued and attempted to arrest 31-year-old motorcyclist Terrence Sterling.

After the officers spotted Sterling, who police said was speeding and running red lights, they tracked him through the city and eventually pulled their marked cruiser into an intersection ahead of the biker. Trainer, the passenger, was getting out as Sterling rode forward and the motorcycle struck the car door. Trainer then fired his gun twice, striking Sterling in the neck and back.

Trainer, 28, told police he had heard the bike revving before it came "violently" toward him and pinned his leg between the door and the car, according to the internal police report. He said he fired because he feared for his safety, as well as Palmer's.

But after re-creating the incident and examining Trainer's injuries, which the report described as superficial, police said they determined the officer's leg had been struck by the car door but was never pinned.

The 34-page report also concluded that Sterling was trying to maneuver around the cruiser, not ram it. And investigators noted that Trainer told them that, other than Sterling's reckless driving, he did not have any reason to think the motorcyclist may have been "armed and dangerous."

Trainer's decision to shoot "was not in defense of his life, nor was it in defense of the lives of others," according to the report.

Trainer, who has been on the force since 2012, is on paid administrative leave. He did not return calls for comment. Palmer could not be reached for comment.

The shooting of Sterling at Third and M streets NW prompted protests and immediately raised questions about the officers' conduct. Mayor Muriel E. Bowser (D) ordered Trainer's name made public soon after the incident, breaking with long-standing policy, and authorities revealed that the officer had failed to turn on his body-worn camera before the shooting. In August, federal prosecutors who investigated the shooting determined there was not enough evidence to file criminal charges against Trainer.

The internal review by the department said there were numerous lapses and judged the shooting "unjustified." Police officials have recommended Trainer be fired. If the officer challenges that finding, a public tribunal could occur early next year.

Three officials with knowledge of the case have said that Palmer, who has been on the force for nearly four years, was suspended for 20 days for administrative infractions, including engaging in an unauthorized pursuit.

The internal affairs report is the most detailed account of the shooting to date.

Jason Downs, an attorney for the Sterling family, said it bolsters the family's contention that there was no reason for police to shoot the motorcyclist.

The internal investigation's "findings with regard to lack of provocation and lack of injury to Officer Trainer are completely consistent to what the witnesses have said from the beginning and what the family has known to be true for the beginning," Downs said.

Sterling's family has filed a $50 million lawsuit against the officers and the city.

Dustin Sternbeck, the chief spokesman for D.C. police, declined to comment on the internal report.

As part of their review, police investigators considered statements by Trainer and Palmer. The investigators also reviewed statements from nine civilian witnesses and six officers who arrived after the shooting.

The department prepared a crash reconstruction report, and investigators studied police radio transmissions, the autopsy report and footage from cameras that recorded the officers or Sterling at various points around the city. There was no video that captured the shooting, according to the report.

At about 4:20 a.m. Sept. 11, officers got a call about a motorcycle in the Adams Morgan neighborhood. The motorcycle ran several red lights and one police official said he spotted it driving in excess of 100 mph, according to the report. An autopsy later determined that Sterling's blood alcohol level was twice the legal limit, and he tested positive for marijuana.

According to the internal report, one police sergeant, who heard a lookout for the motorcycle and saw it pass by, went on the police radio to tell officers not to pursue over traffic violations. The report detailed that a second sergeant then saw Trainer and Palmer's vehicle with its emergency lights on and also went on the radio to say that officers should not pursue the motorcycle.

Trainer later told investigators that he and Palmer believed the motorcycle posed a threat to officers who were on foot or on bikes, as well as to pedestrians, the report said.

Trainer told investigators that he and Palmer drove through various parts of Northwest Washington "aggressively canvassing" for the motorcycle.

When the officers arrived at Florida and Rhode Island avenues NW, they stopped for a few seconds to listen, according to Trainer's account detailed in the report. The officers heard the motorcycle blocks away on New Jersey Avenue and drove toward the sound.

Later, the officers saw the motorcycle stopped at a red light at Third and M streets in Northwest, near the Third Street Tunnel. Sterling's family has said they believe the HVAC technician from Fort Washington had been at a party and was headed home.

The officers pulled into an intersection in front of the bike to make a traffic stop. Trainer told investigators, he began to exit the car holding his gun pointed down. He said he put his right foot on the ground.

Investigators relied on witness statements and physical evidence to develop a picture of the critical seconds that followed.

Trainer told investigators that Sterling looked at him, drove forward and seemed to be trying to run him over, according to the report. He said Sterling ignored commands to stop. When the motorcycle hit the door, Trainer said he felt pain in his leg and fired.

The investigators concluded Sterling was actually trying to position his motorcycle between the squad car and the sidewalk to flee. Had Trainer not opened the door, according to the accident reconstruction, the motorcycle would have cleared the car.

The recreation of the accident by investigators, as well as photographs of Trainer's right knee, revealed that his injuries were "inconsistent" with having his leg pinned, the report found. It also noted that video of Trainer giving Sterling medical attention showed the officer kneeling "with all of his weight bearing down on both of his knees," thereby providing further evidence his injuries were not severe.

"These facts refute Officer Trainer's assertion that his leg was pinned between the door and rocker panel of the scout-car, which was the premise as to why he discharged his service pistol at Mr. Sterling," the review found.

The report said that officers are not allowed to fire their weapons at moving vehicles, unless deadly force is being used against them or someone else. It also said officers should avoid tactics that put them in a position where a vehicle could be used against them.

"It should be noted that Officers Palmer and Trainer violated several policies, placing themselves in an unsafe position, and had they followed Department policies; Officer Trainer would not have been in a position to use force on Mr. Sterling," the report said.