WASHINGTON (AP) — Federal officials said Wednesday that they won't file charges against a police officer who fatally shot an unarmed black motorcyclist last year in Washington, D.C.

The U.S. Attorney's Office for the District of Columbia said in a statement that there was insufficient evidence to prove the city police officer used unreasonable force or was not acting in self-defense.

The officer, Brian Trainer, shot Terrence Sterling after a high-speed chase that ended with the 31-year-old revving his motorcycle into a police cruiser's door, according to the statement. Federal officials said the level of alcohol in Sterling's blood was 0.16, twice the legal limit. They said he also tested positive for marijuana.

Federal officials said the chase began after Sterling pulled in front of the police cruiser that was stopped at a red light.

"Mr. Sterling looked over his shoulder in the direction of the officers and then accelerated at a high rate of speed through the red light," the statement said.

A chase ensued, covering 25 city blocks, federal officials said. Sterling allegedly drove 100 mph or more while narrowly missing pedestrians and cars.

The September shooting led to sustained protests and attracted national attention from activists concerned about police brutality. Sterling was a heating and air-conditioning technician from Fort Washington, Maryland.

Sterling's parents filed a $50 million wrongful-death lawsuit, claiming that Sterling posed no threat and that the officer was negligent when he failed to turn on his body camera.

City officials have acknowledged that the officer, who has been on administrative leave since the shooting, did not turn on his camera, and the city has since ordered 911 operators to remind officers to activate their cameras.

The Metropolitan Police Department released a statement Wednesday that said Trainer will remain on administrative leave as the department begins its own investigation now that the federal probe is over.

The department has not specified the race of the officer, but Jason Downs, the lead attorney for Sterling's family, has said his understanding is the officer is white.

Downs told DC television station Fox 5 on Wednesday that there was "no good reason for the government to decline to prosecute under these circumstances."

"We have to acknowledge that this is another young man that was unarmed, that was killed by a police officer," Downs added. "This is why people believe that there are two justice systems: one for the police officers and one for the rest of us."

Sterling's death prompted protests by activists affiliated with the Black Lives Matter movement. Steven Douglass, a youth minister who knew Sterling and organized protests, told The Associated Press on Wednesday that decision not to prosecute is a "smack in the face."

"The community doesn't feel safe," he said. "We now walk around with murderers who we pay with our tax dollars to protect and serve. We will protest and let it be known that we as a community will not be accepting this decision."