ETHAN SAYLOR would be alive today if Frederick County sheriff’s deputies had exercised good judgment and restraint.

Instead, they ignored explicit warnings from the caretaker who accompanied Mr. Saylor, who had Down syndrome, and physically confronted him over an unpaid $12 movie ticket. In the ensuing scuffle, he died of asphyxia. The Maryland medical examiner’s office ruled his death a homicide. A grand jury declined to bring criminal charges against the three off-duty deputies, who were working as security guards at the movie theater in Frederick.

That shouldn’t be the end of the story. With good reason, the Justice Department is now investigating the incident as a civil rights case.

Charles A. Jenkins, the Frederick County sheriff, says he is confident that the conduct of the deputies — Lt. Scott Jewell, Sgt. Richard Rochford and Deputy 1st Class James Harris — was beyond reproach. Really?

Mr. Saylor, 26, had just watched “Zero Dark Thirty” at a Regal Cinema multiplex Jan. 12 and wanted to watch it again, even though he hadn’t paid for a new ticket. Before the deputies confronted Mr. Saylor, the young woman who was caring for him implored them to “wait it out” and let her handle the situation. She told the deputies that Mr. Saylor had Down syndrome, that he would refuse to comply with their orders and that he was likely to curse them. Even after the deputies approached Mr. Saylor, the caretaker implored them not to touch him, saying he “will freak out” if touched.

And that’s what happened, according to recently released witness statements. Despite the caretaker’s warnings, the deputies moved on Mr. Saylor, who swore at them, and hoisted the 294-pound man from his seat. He panicked, screeched in pain, screamed for his mother, struggled and, moments later, crashed to the ground in a heap with the deputies. With at least one deputy on his back, Mr. Saylor was handcuffed. Moments later, he stopped breathing.

Of the nearly 20 witnesses who saw at least part of the confrontation, many understood immediately that Mr. Saylor was mentally impaired. That, along with his caretaker’s entreaties, should have clued the deputies to back off. When they approached him, he was sitting in his seat, using his cellphone, bothering no one.

Their actions suggest they lacked training in crisis intervention or dealing with the disabled. That’s inexcusable.

One witness, an elderly woman, asked one of the deputies why they couldn’t have let Mr. Saylor alone. He told her they had acted at the behest of the theater manager.

That’s a pathetic excuse for their horrendous judgment. A lawyer for the sheriff’s office now says that Mr. Saylor was trespassing. Yes — and that’s just the sort of minor infraction that police ignore all the time.

It remains to be seen whether the federal government will act against the deputies, or whether a court will find they violated Mr. Saylor’s rights. What’s become clear from the statements of the witnesses is that cool heads and common sense were absent in the law enforcement officers at the scene. A man died as a result.