AFTER A DELAY of 18 months, there is finally a chance for justice in the case of John L. McKenna, the University of Maryland student who allegedly was beaten and clubbed savagely, without cause, by Prince George’s County riot police.

Scores of police, students and onlookers watched three Prince George’s officers pummel Mr. McKenna on the evening of March 3, 2010, as students celebrated the Terrapins’ basketball victory over Duke. Mr. McKenna was unarmed and non-aggressive, and — as video footage appears to make clear — he had done nothing to provoke the officers. The victim was beaten so badly with batons that staples were required to close the wound to his head. The blows continued even after Mr. McKenna lay crumpled on the ground.

Despite that, there was no official response to the incident until weeks later, when a lawyer for Mr. McKenna released the video showing the incident. Until then, police had engaged in what looked like a cover-up; they at first charged Mr. McKenna — wrongly — with attacking officers and their horses. Ludicrously, they claimed that Mr. McKenna’s injuries were caused by retaliatory blows from the horses.

That story, and, apparently, a subsequent lack of cooperation from some county police officers, contributed to the delay in bringing charges against two of the officers allegedly involved in the beating — Reginald Baker and James J. Harrison. They were indicted Tuesday by a Prince George’s grand jury, charged with first-degree assault, a felony, as well as second-degree assault and misconduct in office, misdemeanors.

It’s likely that nothing would have come of this sickening incident were it not for the fact that Mr. McKenna and his family had the means and the savvy to hire a private investigator who found the video. That’s deeply disturbing, and it raises questions about what further reforms are needed in the Prince George’s police department, whose record of brutality triggered six years of federal oversight, ending in 2009.

It’s encouraging that county Police Chief Mark A. Magaw has insisted on new policies for riot police. They include requiring officers to wear helmets imprinted with visible ID numbers, to avoid the problems in identifying officers that apparently were a factor in this case’s delays. Another new policy puts riot officers under tighter supervisory command and requires that internal affairs investigators be on the scene when disturbances are expected at the university.

Those measures send a positive signal that Chief Magaw will not tolerate further incidents of police brutality. That has been reinforced by the new state’s attorney, Angela Alsobrooks, who sought the indictments and stressed that the investigation is ongoing, and by the new county executive, Rushern L. Baker III, who invited the Justice Department and the FBI to launch their own investigation of the case as a possible civil rights violation. With such leadership, the county may yet overcome the stain that the beating of Mr. McKenna has left upon its police force.