Police learned of the interviews at 7 p.m. The FBI planned to interview about 40 officers Thursday night and Friday, police said.
No subpoenas nor warrants were issued, and the FBI did not provide a list of names of officers that will be interviewed, police said.
During a 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 taken by a student from a dorm room window shows John McKenna being beaten by police, and charges against the student were dropped. In the video, McKenna half-jogs, half-dances down the sidewalk and stops when he is cornered by two officers on horseback. Then, three officers in riot gear run toward McKenna, slam him into a wall and beat him with batons. In the video, the beating appears unprovoked.
Police initiated internal, criminal and civil rights investigations. The FBI began investigating in April to see if civil rights laws were violated.
Three officers on the videotape have been identified and put on leave. FBI spokesman Richard Wolf did not say if the three officers suspended after the incident were among those being interviewed, the Associated Press reported, but county police union president Vince Canales said the officers being interviewed were all rank-and-file officers and did not include the officers suspended after the incident. From what he has heard from officers, the interviews have focused on details about where each officer was that night and what their roles were.
"They're very simple knock-and-talk interviews about what occurred," he said. "They have been cooperative, providing whatever insight they can."
Chief Roberto Hylton said a deputy chief told him Thursday night that FBI agents were knocking on the doors of several county officers to interview them about the events that led to the beating of McKenna, who was one of dozens arrested that night.
County police arrested 28 people that night, but charges were later dropped against many of them, including McKenna. At least one student was acquitted for lack of evidence.
The department's internal investigation is mostly done, but officials are cooperating with county and federal prosecutors, said county police spokesman Maj. Andy Ellis. No other officers have been suspended, but Ellis did not know if other officers were under investigation.
This round of interviews of officers was a positive sign to attorney Terrell Roberts, whose office is representing nine plaintiffs, including McKenna, planning civil lawsuits against the department. His office represented about 10 students who were charged that night, and those charges -- ranging from disorderly conduct to assault -- have been dropped.
Roberts said he is hopeful the investigation will improve things in the county.
"It makes officers aware that somebody is going to hold them accountable," he said. "It's not the county itself that's going to do that. Somebody is reaching in and doing it, but it's necessary. Obviously they have not done a good job of policing themselves."
County executive-elect Rushern Baker told The Associated Press on Friday that the FBI had briefed him about the ongoing corruption probe in the county but that he had not been told about the latest round of police officer interviews.
"They want to cooperate with the incoming administration, and I assured them that we would be cooperative," Baker said. "We cannot let the investigation stop us from delivering for the citizens."
Prince George's County police called the FBI interviews a highly unusual investigative practice. They come following sweeping corruption investigations in the county that resulted in the arrests of three police officers. Also, The Washington Post reported this week that at least 46 Prince George's officers are either suspended or have been assigned to administrative duties for alleged misconduct. Earlier this week, an officer was accused of sending sexually explicit text messages to a woman after taking her identity theft complaint.