Federal authorities have joined the investigation into the alleged beating of a University of Maryland student by Prince George's County police, Chief Roberto Hylton said.

During a victory celebration in the streets of College Park after a March 3 Maryland basketball victory over Duke, police on horseback confronted students.

Initially, police said one of the students attacked officers and their horses. The student was charged with felony assault.

But a videotape of the confrontation tells a different story, and charges against the student were dropped.

Video shows Jack McKenna being beaten by police.

"It's like something out of a bad movie," said his grandfather, Jim McKenna. "He retreated. He stepped back at least one step and I think maybe two, and they sat down on him."

A retired Montgomery County Circuit Court judge, Jim McKenna thinks the officers involved should be in jail, charged at least with assault with intent to maim.

"They see a kid coming their direction who's happy because the team had won, and what, precisely, was their motivation to go over and try to beat him to death?" he said.

Two officers have been suspended -- including the writer of the statement of charges -- and other suspensions are expected, police said. The department believes it has identified all the officers seen in the video -- with some of the officers stepping forward voluntarily -- but is not releasing those identities because of threats, police said. All suspended officers will be identified by name once all suspensions have been made, police said.

"There's a public interest in this and there's a public right to know what's happening with their police department," said Prince George's County police Maj. Andy Ellis. "We saw a videotape that is disturbing, and so there is a right for the public to know, and we must balance that right with due process rights of the officers involved and also safety."

Ellis noted that in such a situation as the Maryland celebration, officers are dealing with fires being set and items being thrown, but the department is reviewing its procedures in such situations.

"I respectfully ask the public and the media at large to await passing judgment and allow the established internal investigative process to work," said Prince George's County Fraternal Order of Police President Vince Canales.

Authorities are conducting an internal investigation, a criminal investigation and a civil rights investigation. FBI agents are reviewing the video and all the events of that night to see if civil rights laws were violated, said spokesman Rich Wolfe.

An officer pulled off the student's bandage and told him not to report an injury, said the student's attorney, Terrell Roberts, on "Today" Wednesday morning.

Prince George's County police are conducting an internal investigation to determine which officers were involved in the incident.

It was an isolated incident, and the actions of a few officers should not taint the entire department, Hylton said.