AN FBI agent shot a man on a moving Metro train on the Red Line in December, an incident that might have raised some pertinent questions in the public’s mind. Pertinent or not, those questions went unanswered for more than five months as an investigation plodded along under the auspices of law enforcement agencies apparently indifferent to a public accounting.

It was only last Tuesday when Maryland prosecutors announced the agent, Eduardo Valdivia, had been indicted on a charge of attempted murder that answers emerged to even basic questions about what happened. Neither the FBI nor Metro seem to have gotten the memo that the public will no longer tolerate a cone of silence on officer-involved shootings.

We now know that Mr. Valdivia was on his way to work when he was approached by a man who asked for money. According to prosecutors, the panhandler cursed after the agent refused him money, the agent took offense and the panhandler then accosted the agent, without touching him. At that point, Mr. Valdivia drew his handgun and shot the man twice at short range, inflicting grievous but not life-threatening injuries.

A video of the incident was recorded by an onboard Metro camera, but the transit agency has refused to release it. In fact, even though Metro Transit Police completed its initial investigation after just six days, it told the public only that the agent had shot a passenger who approached him “following a verbal exchange.” Left to the imagination was whether the man he shot was an acquaintance or a stranger, a terrorist or a suspect in an ongoing investigation.

Neither Metro nor the FBI offered an explanation for the shooting, despite the fact that within days the agent agreed to an interview with prosecutors in Montgomery County. Even basic questions continue to go unanswered by the FBI. “We cannot provide any further comment,” the agency told us when we asked whether Mr. Valdivia was on duty at the time of the shooting.

The FBI says it has fully cooperated with the investigation. Yet it has not provided other possibly relevant information that many police departments would release. For example, had Mr. Valdivia received training in de-escalation techniques? Had he been trained to recognize mental illness?

FBI policy allows agents to use deadly force only when they believe they or another person faces an individual who poses an “imminent danger of death or serious physical injury.” In the absence of the public release of the video, it is impossible to judge whether Mr. Valdivia adhered to that policy, or if his decision to open fire was objectively reasonable, the standard set by the Supreme Court. Nor is it clear whether the FBI’s policy was even in effect at the time of the shooting, when he was commuting to work.

That’s the trouble with law enforcement covering for its own with a veil of silence. Even in the case of a shooting in a venue as public as a Metro car, the public is kept in the dark. That serves neither the public nor the cause of justice.

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