The FBI is conducting a preliminary investigation of the Prince George's County Detention Center to determine whether guards deliberately allowed rapes and sexual assaults to occur in the jail, in violation of federal civil rights law, a U.S. Justice Department spokesman said yesterday.

Under the law, inmates have a right to be free from harm while in custody, and guards who violate that right can be indicted, according to U.S. Justice Department spokesman John Wilson.

"The civil rights division of the U.S. Justice Department has the FBI doing a general inquiry to determine whether there is federal jurisdiction in this matter," said Wilson, spokesman for the department's civil rights division. "The law says simply that it's a federal crime for a law enforcement officer to deliberately violate someone's civil rights."

Wilson said the Justice Department initiated the investigation as a result of a series of articles in The Washington Post.

The articles reported that male inmates rape or sexually assault other male inmates in the jail about a dozen times a week, according to guards and inmates. The articles described a dozen rapes and sexual assaults that had occurred in the jail during the last four years.

In each case, the victim's description of the assault was corroborated by the rapists and/or medical evidence or other evidence. The articles named rapists and victims except in four cases in which victims did not permit their names to be used.

Jail officials, who did not have any comment yesterday on the investigation, have said that estimates of a dozen rapes a week are an exaggeration.

In eight of the cases, guards apparently were unaware of the rapes because they cannot see into most cells from their posts, and the cells are where the rapes occur. In two of those eight cases, the guards' view was also blocked by newspapers or trash bags, which inmates draped over the cells.

In four cases, however, there apparently were other reasons for the guards' inability to protect the inmates, according to the victims and the rapists. In the case of Kevin Parrish, who was brutally beaten because he refused to give a group of inmates oral sex, the guard on duty was asleep. In a second case, the rape of a 24-year-old Suitland man, the guard was not present. When Ronald Fridge was raped, the guard walked away just before the rape; and in a fourth case of an Air Force lieutenant charged with disorderly conduct, the guard refused to help the lieutenant when he complained to him that he was being threatened with rape. Shortly afterward, the lieutenant was raped.

The FBI probe focuses on a different aspect of the problem than a special grand jury appointed by State's Attorney Arthur A. Marshall Jr. The grand jury is concerned primarily with indicting men who admitted in the newspaper series that they had raped other men. So far, the special grand jury has not broadened its scope to examine the role of the guards, according to sources.

If the FBI finds evidence of deliberate wrongdoing on the part of guards, the FBI will refer the matter to the U.S. Justice Department's civil rights division, which must decide whether to bring the evidence to a federal grand jury, according to FBI spokesman Andrew Manning. The penalty for knowingly breaking the federal civil rights law is up to 10 years in prison and/or a fine of $1,000-$10,000, Manning said.

"This isn't your usual civil rights complaint," said Manning, adding that the investigation of guards' actions possibly leading to jail rapes appeared to be a novel one.

Manning refused to name the specific cases of rapes or sexual assault that the FBI would investigate, saying only that the FBI planned to interview victims and others and already had contacted the jail.