The attorney for the family of an unarmed motorcyclist who was shot to death by a DC police officer in 2016 says a DC grand Jury may not have reviewed all available video evidence in the case before the US Attorney announced a decision not to indict the officer involved.

"One of the most critical pieces of evidence in the case wasn't even being discussed," said attorney Jason Downs Thursday.

RELATED: DC officer who shot, killed Terrence Sterling won't face charges

Downs represents the family of shooting victim Terrence Sterling who was killed by DC police officer Brian Trainer after what authorities described as Sterling's reckless, high-speed attempt to get away on a motorcycle from pursuing police.

Downs says family members questioned authorities Wednesday about wether evidence from a camera at the intersection of 3rd St. NW and M St. NW operated by Homeland Security exists. If so, the family wants to know if it was presented to the grand jury assisting in the review of the case. Prosecutors had no answer for family members, according to Downs.

"We have requested this camera video early in the process. The US Attorney did not even describe what is on that footage or, if it doesn't exist, why doesn't it exist," Downs said.

Authorities have released body camera video taken moments after the shooting. Officers did not have cameras turned on when the shooting happened.

A spokesman for DC's US Attorney's office said there was no comment on the concerns about potentially missing video raised by the Sterling family.

RELATED: Terrence Sterling: Unarmed & killed by police, his family speaks out

Prosecutors and investigators conducted a comprehensive review of the incident including DC Department of Transportation video, closed circuit TV video and cell phone camera video, according to a statement from the US Attorney's office Wednesday.

Downs added that Sterling's family is frustrated that prosecutors made a decision not to indict officer Trainer without asking grand jurors to decide for themselves.

"Not allowing the grand jury to vote on this evidence silences the voice of the community and the family is deeply concerned about that," Downs said.

The US attorney has the power to indict without a grand jury finding.

According to the US Attorney's statement there was insufficient evidence for an indictment.

The statement described what investigators believe happened in the final seconds of the fatal encounter:

"Mr. Sterling revved his motorcycle and then accelerated and turned it toward the cruiser’s exposed passenger side. The officer, who was partially out of the cruiser, never got a chance to fully exit the vehicle. He felt the impact of the motorcycle hitting the cruiser’s door. The impact caused by the advancing motorcycle caused a dent in the cruiser’s open door and a bruise to the officer’s knee. The officer reacted by immediately firing two rounds at Mr. Sterling through his front passenger window."