The FBI is investigating allegations that seven Prince George's County corrections officers beat an argumentative prisoner so severely last year that he was permanently brain damaged.

FBI spokesman Peter A. Gulotta Jr. said his agency is conducting a criminal investigation into the treatment Christopher Byron Simms, 29, received in jail in September. The allegations came to light recently when a civil rights lawsuit was filed on the man's behalf.

The FBI probe is at least the third ongoing federal investigation of alleged use of excessive force by county law enforcement officers.

A county corrections spokeswoman said she could not comment on the incident because of the pending lawsuit. But in a December letter to Simms's attorney, Corrections Director Barry L. Stanton said his officers did not use excessive force.

"The obvious injuries sustained by Mr. Simms were a product of his own actions," Stanton wrote. Stanton said his department's internal affairs division investigated the incident and cleared the officers of any wrongdoing.

The lawsuit filed by attorney Timothy F. Maloney in U.S. District Court in Greenbelt contains the following account and allegations:

Simms had been jailed on criminal charges for almost two months by the morning of Sept. 11, when he repeatedly asked a guard to release him from his cell. The officer refused to let any of the prisoners out, though normal lockdown hours had ended.

The guard warned that if Simms did not stop asking to be let out, she would "call her boys." Simms continued to argue with the guard, identified only as Officer Hardesty in the lawsuit, and she summoned the Department of Corrections emergency response team.

Those officers dragged Simms to a common area of the cellblock, beating and choking him while the other prisoners looked on, the lawsuit alleges. An ambulance was called several hours later, and Simms was taken to Prince George's Hospital Center, according to the lawsuit and Maloney.

County Attorney Sean Wallace, whose office represents the Department of Corrections, gave a different account of the incident. He said Simms attacked a corrections officer and struggled violently with the officers who were summoned to subdue him.

That version was supported by Stanton in his December letter to Simms's attorney.

"There is no indication that any excessive force was used toward Mr. Simms," Stanton wrote. ". . . A degree of necessary force was used to control and subdue him as a result of his combativeness and unwillingness to submit to lawful orders of staff."

Simms had been jailed July 16, 1998, on a charge of second-degree assault and fourth-degree sex offense after he allegedly grabbed the breast of a United Parcel Service worker in Laurel and tried to unbutton her blouse.

Three days after the jail incident, the state's attorney's office dropped the charges against Simms because the woman who accused him of assaulting her did not appear in court, officials said.

Simms was hospitalized for two months at Prince George's Hospital Center and the National Rehabilitation Hospital as a result of injuries suffered during the altercation, including a facial fracture and other head trauma. He was unable to walk or eat solid foods and was incontinent, according to the lawsuit.

Simms has since regained his ability to walk and eat solid food, and he is no longer incontinent. But he does not recall what happened that day, according to his father, Byron B. Simms. He is easily confused, needs to be told to do basic things such as dress himself or shower, and cannot be left alone, Byron Simms said.

"I'm just looking for accountability," Byron Simms said. "What happened to Christopher should not have happened."

Simms, who now lives with his father in Columbia, attends a vocational rehabilitation program on weekdays but cannot drive a car, Byron Simms said. Because of the brain damage his son suffered, Byron Simms said, he has become Christopher's legal guardian.

At the time of the incident, Christopher Simms, who is 5 foot 8, weighed 160 pounds, according to court records and relatives. His son has gained about 70 pounds since then, Byron Simms said.

The lawsuit filed by Maloney alleges that county corrections officers beat Christopher Simms and violated his civil rights. It seeks $50 million in compensatory damages and $50 million in punitive damages.

In addition to the Simms case, the FBI is investigating whether the county police department's canine unit, accused of excessive force in at least 13 pending civil suits, has engaged in a pattern of brutality.

The FBI also is investigating an incident last month in which an unarmed robbery suspect was seriously injured by a county police dog. Police officials said the dog was released after the man attacked officers and tried to run away.

CAPTION: A civil rights suit has been filed on behalf of Christopher Byron Simms.