Elahe Zanganeh joins other friends and family of Bijan Ghaisar on Jan. 26 outside the Interior Department in Washington. Ghaisar was shot and killed by two U.S. Park Police officers in Northern Virginia on Nov. 17, 2017. (Toni L. Sandys/The Washington Post)

POLICE ARE accountable to the public, much as other agencies of government are. So is the FBI. Those basic precepts have somehow been discarded in the case of a 25-year-old accountant from McLean who was shot to death by two U.S. Park Police officers last fall — an act whose justification, if any, remains unknown and unexplained.

There is no indication the man, Bijan C. Ghaisar, was armed. There is no indication he posed a threat to the two officers who shot him, or anyone else. At the time the police shot him, he was at the wheel of his vehicle, which was rolling slowly away from the officers, who, inexplicably, had approached him with guns drawn. That’s when they opened fire, hitting him in the head.

Why did the officers shoot? Neither the Park Police nor the FBI, which is handling the investigation, will say. Why did they approach Mr. Ghaisar’s car with guns drawn? Neither the Park Police nor the FBI will say. Why have the officers not been identified?

After six months, how is it possible that no information has been released, nor action taken to resolve the case? Can anyone now be shot in their vehicle by police, for any reason or no reason whatsoever, without consequences? Is indefinite silence all that can be expected from the authorities in the aftermath of a police shooting?

Aside from acknowledging that an investigation into the shooting of Mr. Ghaisar is ongoing, the FBI refuses comment. It has had nothing to say — despite the release, in January, of a clear, complete video of the Nov. 17 incident, recorded by the in-car camera of a Fairfax County police cruiser, which tailed the Park Police during the pursuit. (The video was released by the Fairfax police chief, Edwin C. Roessler Jr., whose officers witnessed but took no part in the shooting.)

Nor will the FBI director, Christopher A. Wray, agree to speak with Rep. Don Beyer (D), who represents the district in Northern Virginia where the incident took place. Mr. Beyer, quite reasonably, requests that the FBI finish its investigation and release a report.

The video suggests that Mr. Ghaisar was shot for the non-crime of annoying the police. He had been involved in a minor fender bender — in fact, it was his car that was hit from behind, on the George Washington Parkway — and then drove away without speaking with the other car’s driver, who called 911.

Minutes later, the Park Police spotted Mr. Ghaisar’s vehicle, a Jeep Grand Cherokee, and gave chase. When Mr. Ghaisar pulled over, the two Park Police officers approached with guns drawn, though no sign of a threat is visible on the video. He then drove away, though not at a high rate of speed, with the police again in pursuit. The same thing happened again. The third time he pulled over, the police blocked his car with theirs and approached him from the side. His car began to roll, though not in the officers’ direction. That’s when they shot him.

None of this makes sense. When police shoot a citizen without apparent justification, is omerta — the gangland code of silence — the best the public can expect?