After an exhaustive review, the Los Angeles Police Department said today that Mark Fuhrman had grossly exaggerated most if not all of his accounts of his racist brutality as a patrol officer but had been allowed to ''act out his prejudices,'' especially against female officers at work.

Mr. Fuhrman is the former detective whose perjured testimony about his use of racial slurs gravely undermined the prosecution in the O. J. Simpson murder trial. The report on him was commissioned nearly two years ago, after Laura Hart McKinny, an aspiring screenwriter, produced tape recordings from the mid-1980's in which Mr. Fuhrman repeatedly used the word ''nigger'' and bragged about brutal exploits as a police officer.

The tapes not only shattered Mr. Fuhrman's reliability as a witness in the Simpson case (he had earlier denied using the racial slur) but further shook public confidence in the police department, which already had a reputation for excessive force in the wake of the Rodney G. King case.

In interviews with Ms. McKinny, Mr. Fuhrman repeatedly said he and others beat, kicked and even fatally brutalized suspects.