WHEN A person is killed by gunfire, it's customary that the police provide basic information to the public. When the gun is discharged by the police themselves, however, different — and unwarranted — standards all too often are applied.

How else to understand the curtain of official silence that continues to shroud the death of Bijan C. Ghaisar, a 25-year-old accountant shot by U.S. Park Police nearly six weeks ago? Mr. Ghaisar, who was apparently unarmed, was behind the wheel of his car when one or two officers opened fire, shooting him several times in the head. He died 10 days later.

It is reprehensible that virtually no information has been disclosed about the incident, either to Mr. Ghaisar's family or to the public. Park Police have said nothing, nor have they released details of the alleged hit-and-run accident on the George Washington Memorial Parkway that triggered an 11- ­minute pursuit culminating with the shooting. Fairfax County police, whose officers tailed the Park Police vehicle and recorded the shooting with their dashboard camera, are mum. So is the FBI, to which the Park Police shifted the investigation a few days after the incident.

What could possibly justify so extensive an information blackout? Did a hit-and-run accident actually occur in Alexandria, as the Park Police said? If so, why has no report surfaced of anyone having been injured, or of any damage to a vehicle that may have been struck by Mr. Ghaisar? Since when are hit-and-run accidents accorded the silence usually reserved for state secrets?

On what grounds do the authorities justify their decision thus far not to identify the officer or officers who opened fire, killing Mr. Ghaisar? On what grounds do the FBI and Fairfax County police continue to withhold the video of the incident? On what grounds are they entitled to keep Mr. Ghaisar's family in the dark, as well as the public, on the basic question of why officers discharged their weapons?

Mr. Ghaisar grew up in McLean, lived in Tysons Corner and worked for his father's firm. The car he drove bore vanity plates with his given name: BIJAN. Was ethnic profiling a factor in the Park Police's decision to pursue him or to shoot him? And if that question causes official indignation, then what other explanations should the public consider more plausible?

The Fairfax County Board of Supervisors as well as the county's police chief, Edwin C. Roessler Jr., have called for the video to be released. So has Mr. Ghaisar's family, which encountered a locked door when they went to a staffed Park Police station on Christmas Eve to plead for information about the death. The Park Police has referred the family to the FBI, which has been tight-lipped.

The authorities' indiscriminate silence makes a mockery of the open society that distinguishes the United States from autocracies and dictatorships. The longer it continues, the more the public will suspect a coverup. How that serves anyone's interest is a question officials might ponder.