An employee at a Southeast Washington group home for mentally retarded adults has been charged with sexually assaulting a resident of the facility.

The employee, Fred Fagan, was seen in the victim's room by another staff member, who opened the door and saw Fagan, naked from the waist down, assaulting the man, according to prosecutors and police testimony.

Charged with second-degree sexual abuse, Fagan, 56, appeared yesterday in D.C. Superior Court. A judge ordered that he be fitted with an electronic monitoring device to track his whereabouts while the case is pending.

D.C. police Detective Vincent Spriggs, who investigated the case, testified that the other employee was horrified by what she saw on the morning of Aug. 19. "She slammed the door and screamed and told other staff," Spriggs said.

The victim, who is middle-aged, is entirely dependent on the staff of the home, Spriggs testified. "He's unable to speak and care for himself," Spriggs said.

One of 11 employees at the group home, Fagan was responsible for helping residents with such functions as eating and bathing.

When the employee encountered the men in the room, the victim was naked and had his hands over his eyes, Spriggs testified.

The group home, in the 2600 block of Branch Avenue SE, is operated by ResCare, a Louisville-based company that cares for more than 30,000 disabled people around the country.

Steven Dale, executive director of the company's operations in the District, said the other employees on duty that morning did exactly what they were supposed to do.

The employee who said she witnessed the attack contacted her supervisor, and the home's managers began trying to piece together what happened. By late morning, they decided that the police needed to be called, and by about 11 a.m., Spriggs had arrived.

With the victim unable to talk, the investigation was more complicated than the typical sex crime, and Fagan was not immediately arrested. The D.C. inspector general's office joined the investigation.

After an interview at the inspector general's office on Oct. 12, Fagan was arrested and charged by the U.S. attorney and the inspector general.

Dale, of ResCare, said that he could not immediately say how long Fagan had worked at the group home. Fagan, of the 4500 block of Halley Terrace SE, has been on administrative leave since that day, Dale said.