Brandon Jackson, brother of Anton Black, and Janell Black, Anton's mother, in Greensboro, Md., on Jan. 3. (Courtland Milloy/The Washington Post)

THE DEATH in 2013 of a 26-year-old man with Down syndrome after an encounter with sheriff’s deputies at a Frederick County movie theater prompted Maryland lawmakers to mandate police training that included how to calm excited subjects instead of automatically using force. After watching the video of 19-year-old Anton Black’s fatal encounter with police authorities on the Eastern Shore of Maryland, we have to wonder about the effectiveness of that regimen. The tragic death of this young black man was needless and raises troubling questions that must not go unanswered.

Did police in the town of Greensboro not get the message about the need to de-escalate, not inflame, situations? Why did it take months of prodding from Mr. Black’s grieving family before the primary officer involved in the incident was placed on administrative leave? Should this officer even have been hired in the first place, considering his history checkered with allegations of excessive force? Would different actions have been taken if Mr. Black had been white?

Mr. Black died Sept. 15 following a physical encounter with police after an officer responding to a call of a child abduction chased, Tasered and restrained him. The medical examiner last week ruled the death accidental, saying he suffered “sudden cardiac death.” Underlying heart issues and bipolar disorder contributed to his death, as did “the stress of his struggle” with police, according to the medical examiner’s report. Caroline County State’s Attorney Joe Riley subsequently issued a statement that “there is not currently enough evidence to establish probable cause to seek an indictment” and denied a request from Mr. Black’s family that a grand jury investigate the case. He said his office is not empowered to prosecute tragic acts but would continue to evaluate “all evidence that is shared.”

Release of police body-camera footage showed the disturbing sequence of events starting with Greensboro Officer Thomas Webster IV (whose hiring had been protested because of a racial incident at a previous job) responding to a 911 call of a child in trouble. That child, Mr. Black’s family said, was a longtime friend, and the father of the young boy said what the caller to police saw as a kidnapping was actually horseplay between friends. After Mr. Black ran away, the officer radioed that the subject was schizophrenic. How he came to that diagnosis is unclear, but if he believed that was the case, it makes his subsequent actions all the more questionable. Mr. Black had run home, but the door was locked, so he locked himself in a car. He was by himself, not armed and not posing a danger to anyone — but Mr. Webster used his baton to smash the window of the car and stunned Mr. Black with a Taser. A struggle followed, involving other officers and a bystander. After Mr. Black’s collapse and unsuccessful efforts to get him breathing, Mr. Webster can be heard telling the young man’s mother, “Well, we’re just doing the best we could. I’m sorry.”

More than an apology is needed. Greensboro officials need to bring in outside experts to review the actions of police and ensure accountability. Attorneys for Mr. Black’s family want the U.S. Justice Department’s Civil Rights Division to investigate. Mr. Riley has already shared information with the U.S. Attorney’s Office, and we hope that will lead to federal review of these events.