The FBI was unable to question at least 25 colleagues of four police officers charged in a videotaped beating because the officers would not voluntarily cooperate, a union lawyer said.

A Los Angeles County grand jury has reconvened to hear evidence about officers who stood by and watched the March 3 attack on a black motorist that stirred national outrage after it was captured on videotape by an onlooker and played on television.The defendants, Sgt. Stacey Koon, 40, and Officers Laurence Powell, 28, Timothy Wind, 30, and Theodore Briseno, 38, were scheduled to enter pleas Tuesday to charges including assault and brutality.

If convicted, they could get up to 4 years to 73/4 years in prison.

Cecil Marr, an attorney for the Los Angeles Police Protective League, which represents the 8,300-member force, said he was present at five interviews Monday at the Foothill Division that were terminated by FBI agents. That is the division where the four officers are assigned.

"There have been no substantive questions asked (by the FBI) in my presence," Marr told the Daily News of Los Angeles in a story published Tuesday. "The FBI is insisting on only voluntary interviews. Unless the police officer gives up his rights, the FBI is not interested in talking to him."

FBI agents called off interviews with 20 other officers Monday when the investigators were told the officers would not voluntarily cooperate, Marr said.

But Lt. George Aliano, president of the union, said that at least some officers agreed to be interviewed Monday as part of the civil rights investigation. He provided no specific numbers or details of what the officers said.

Agents are looking to see if a pattern of civil rights abuses exists within the station, police Lt. Fred Nixon said.