IF THERE is a lesson in the career of U.S. Park Police Chief Robert D. MacLean, it’s that a lack of accountability is no bar to success.

Mr. MacLean, a 28-year veteran of the Park Police, is being promoted to the top law enforcement position at the Interior Department, a job that entails supervising law enforcement, security and intelligence functions for seven sizable federal agencies. When his promotion was announced in August, the Interior Department lauded his “stellar record.”

There was no mention, however, that Mr. MacLean’s record includes an abject failure to come clean on the outrageous shooting of an unarmed young man by two Park Police officers in a suburban neighborhood just outside Washington two years ago. The man, Bijan Ghaisar , a 25-year-old accountant, was shot to death in his vehicle at close range after he was involved in a fender bender on the George Washington Memorial Parkway. A video of the incident, recorded by a Fairfax County police cruiser’s dashboard camera, strongly suggests the shooting was unwarranted.

Mr. MacLean’s response to that shooting, which to this day has not been explained, has been silence. An unarmed American civilian was gunned down by uniformed federal police under his command, and Mr. MacLean has made no attempt to tell the public what happened and no apparent effort to ensure it does not happen again.

Specifically, he refused to identify the officers who opened fire on Ghaisar, then refused to confirm the two men were in fact Park Police officers when their names — Lucas Vinyard and Alejandro Amaya — were divulged in the course of a lawsuit brought by Ghaisar’s family. Mr. MacLean refused to release the video of the incident, which was finally made public by the Fairfax police.

In terms of accountability, that’s a breathtaking dereliction of duty.

In addition, there has been no explanation from Mr. MacLean, or anyone under his command, of why Ghaisar’s family was treated abusively in the days following the shooting, when their son lay in a coma at the hospital for 10 days before he died. During that time, Ghaisar was attended by Park Police officers, who forbade his parents from touching him or spending more than 10 minutes with him each hour.

After two years, Mr. MacLean is not alone in displaying what amounts to contempt for the public in the Ghaisar case. The FBI, to which Mr. MacLean turned over the investigation three days after the shooting, has been mum. So has the Justice Department, whose Civil Rights Division might reasonably exercise its authority in the matter. The same goes for the U.S. attorney for the District of Columbia, Jessie K. Liu, who would be involved in any decision on whether to bring charges against the two officers.

The United States is not a police state. But make no mistake: It has acted as one in the case of Ghaisar. Official silence that drags on for 22 months in the slaying of a U.S. citizen is unacceptable, unjustifiable and un-American.

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