A severely retarded deaf woman may have been sexually assaulted when she wandered away from the state-run Great Oaks Center for the mentally disabled in Silver Spring on Monday, according to Prince George's County police.

The 26-year-old woman, who was not identified by police, apparently strayed from the facility about 9 p.m. She was found by a police officer two hours later as she walked along Calverton Boulevard about a mile from the center, according to police spokesman Bruce Gentile. Gentile said she was dressed in street clothes and was disoriented.

Police said evidence suggests the woman was raped, but so far they have been unable to question her because of her disability.

Dr. Marvin Malcotti, director of the center, said five security officers patrol the complex, but residents generally are allowed to leave if they wish.

The woman was taken first to Greater Laurel-Beltsville Hospital, and then was taken to the sexual assault center at Prince George's County Hospital, police said.

Tests indicated she might have had "sexual contact," police said.

"This may be a simple assault, but right now we don't know what we have except that it seems there may have been sexual contact of some sort. We're treating it as a rape just to be on the safe side," Gentile said.

Gentile said investigators have tried to question the woman using sign language, but have been unsuccessful.

Police are interviewing residents in the area where the woman was found to determine whether anyone was with her when she left the facility.

Malcotti said the woman had been a resident of the facility for two years and had never left without supervision. He added that she had no history of abnormal behavior and was considered a "good resident."

Since the incident, the woman has been staying with her mother in Gaithersburg, and Malcotti said it was not clear if she would return.

Great Oaks is the second largest facility for the mentally disabled in the state, and houses about 425 residents.

In 1984, a severely retarded woman became pregnant after she was raped while under care at the facility. The U.S. Supreme Court ruled after her case received national attention that she could have an abortion.

Last year, two employes were charged with beating residents. In one case, a staff member allegedly beat a resident in the head with an aerosol can.