IS IT possible that the U.S. Park Police simply don't have enough to do? Or that they hunger for more action than is usually available in their quotidian diet of patrols at national monuments, speeding tickets on verdant parkways and crowd control at occasional protests?

Could that be what possessed two Park Police officers to hit their patrol car's siren and emergency lights, give chase and ultimately open fire on an unarmed motorist whose "offense" was to have driven away after his vehicle was rear-ended in a fender bender on the George Washington Memorial Parkway in November? The man, Bijan Ghaisar, a 25-year-old accountant from McLean, was hit three times in the head. He died 10 days later.

Yes, it's a crime to leave the scene of an accident, even one in which no one was injured and, apparently, no grave damage was done to either vehicle. Mr. Ghaisar should not have done that.

But what in the world possessed the officers to escalate a minor incident involving no serious harm into a chase-and-shoot extravaganza? Police are paid first and foremost for their judgment. Itchy trigger fingers, an inability to exercise restraint and plainly excessive use of force suggest a staggering lack of judgment in the case of Mr. Ghaisar's death.

That, at least, is what can be gathered from the scant information available to the public. Neither the Park Police, who appear to have buried their heads in the ground, nor the FBI, to whom they handed off the investigation, have offered anything resembling a full accounting of the facts. Not to Mr. Ghaisar's family, and not to the public.

That's chilling and an abdication of the most basic obligations of accountability in a democracy. Why haven't the officers who fired their weapons at Mr. Ghaisar been identified? Have they been suspended? Are they still patrolling the GW Parkway? Should drivers on the parkway be worried that they too may be shot in the head if they are rear-ended and drive away?

Why did the officers think that opening fire on Mr. Ghaisar was an acceptable course of action? What is Park Police policy on use of force or pursuit of vehicles? Why has the agency refused to divulge those policies in compliance with Freedom of Information Act requests? Why is all this secret? What do the Park Police have to hide?

And why do Fairfax County police, whose officers were on the scene of the shooting and made a video recording of it, play along with the secrecy game? Are the area's various police departments now following Cosa Nostra rules, which dictate silence among them?

Americans who have lived under authoritarian regimes recognize all this very well — police who are accountable to no one; abuses that go unacknowledged and unpunished; "investigations" that drag on interminably, yielding nothing. A promising young man who loved video games and the New England Patriots is dead, and for what?