With jurors excluded from the courtroom, a reluctant Judge Lance A. Ito today allowed defense attorneys in the O.J. Simpson murder case to play tapes of retired detective Mark Fuhrman boasting to a screenwriter -- amid a flurry of racial epithets and obscenities -- of beating black suspects, falsifying police reports and contriving probable cause to make arrests.

The voice sounded calm, casual, at times almost bored. But the words were explosive and brutal.

"Most real good policemen understand that they would love to take certain people and just take them to the alley and blow their brains out," Fuhrman declared in one excerpt.

In another, while explaining his opposition to the construction of a new police station in South Central Los Angeles, he said, "Leave that old station. Man, it has the smell of niggers that have been beaten and killed in there for years."

Ito, Simpson, lawyers from both sides and spectators listened in stunned silence as Fuhrman's voice resounded through courtroom loudspeakers describing numerous alleged instances of police misconduct.

The celebrity defendant's lawyers offered the interviews, recorded by North Carolina screenwriter Laura Hart McKinny over a nine-year period, as proof that Fuhrman, a key prosecution witness, lied when he testified under oath last March that he had not used the racial epithet "nigger" any time over the past 10 years.

Defense lawyers played tapes or displayed transcript excerpts of 41 instances in which Fuhrman used the slur "nigger" and 17 instances in which he uttered that and other racial epithets and made references to his own or other officers' alleged misconduct.

Fuhrman was briefly assigned to investigate the slayings of Nicole Brown Simpson and Ronald L. Goldman on June 12, 1994. He found crucial evidence against O.J. Simpson, including a bloody glove he said he recovered from behind Simpson's house that matched a glove found at the crime scene nearly two miles away.

In an effort to impeach Fuhrman's credibility, the defense is seeking to persuade Ito to allow the predominantly black jury to hear the taped interviews and read accompanying transcripts. Lead defense attorney Johnnie L. Cochran Jr. has said the tapes could be pivotal in the effort to win an acquittal.

Fuhrman, in an interview with McKinny on July 28, 1994, after he had testified in a preliminary hearing, seemed to agree.

"I'm the key witness in the biggest case of the century," he told her. "And if I go down, they lose the case. The glove is everything. Without the glove, bye-bye."

Calling Fuhrman the "greatest liar since Ananias," a Biblical character who was said in the Book of Acts to have lied to God, defense attorney Gerald Uelmen told the court the tapes were necessary to impeach Fuhrman's sworn denials. Uelmen called the tapes "Los Angeles's worst nightmare" because of their racial invective.

The prosecution, in a 32-page written motion, asked Ito to issue a ruling barring the defense from playing the tapes to the jurors, who were sequestered in their hotel during today's hearing.

Prosecutors argued that Fuhrman's credibility is at issue only with respect to his testimony about discovering the bloody glove, and that he had neither opportunity nor motive to risk planting the evidence.

Calling the tapes "incendiary collateral evidence," the prosecution argued that admitting them as evidence would raise "the specter of a miscarriage of justice" over the trial.

In a news conference, District Attorney Gil Garcetti said he was angry that a police officer, "regardless of the circumstances, has uttered such hateful words." Asserting that Fuhrman was not a key witness, Garcetti said, "This is supposed to be a trial" about O.J. Simpson's guilt or innocence, "not about whether Mark Fuhrman is a racist." Garcetti said there is still "an overpowering case, an overwhelming case" that proves Simpson's guilt.

Ito appeared ambivalent about allowing the tapes to be aired publicly, even out of the presence of the jury. At one point, he told defense lawyers he had already listened to the tapes and read the transcripts. "I don't need to hear any more. . . . I've heard it. I've read it. I've seen it," he said.

But a few minutes later, after listening to some of the excerpts, Ito said that although he already had "ample context" for what Fuhrman had said to McKinny, he would not suppress "information that is of vital public interest."

The judge appeared to be referring to persistent demands by black civil rights organizations here that all the tapes be made public. Black leaders have cited the tapes as evidence of widespread racism in the Los Angeles Police Department, which has been under intense public scrutiny since the 1992 riots that were triggered by the acquittal of four white police officers who were videotaped beating black motorist Rodney G. King.

During the lunch recess, Fred Goldman, Ronald Goldman's father, angrily and tearfully complained in a news conference that by allowing the tapes to be played in court, Ito had subjected the victims' families to a "nightmare" and had allowed the defense once again to divert attention from the evidence against Simpson.

Declaring he was "outraged," Goldman said, "We came to this court expecting a fair trial. My son had a right to it. Instead we get this crap spewed in front of the {television} cameras for two hours."

In one instance on the tapes, describing how he and a partner named Dana allegedly interrogated a black suspect in a baseball field, Fuhrman says, "When I left, Dana goes, No blood, Mark.' No problem, not even any marks, Dana.' Just body shots. Did you ever try to find a bruise on a nigger? It's pretty tough, huh?"

Asked about needing probable cause to arrest a black suspect, Fuhrman retorted, "Probable cause? You're God."

Describing the arrest of a suspected narcotics user, Fuhrman said officers had squeezed a scab left from an old hypodermic injection and reported that the drug use was recent.

"That's not falsifying a report," he said. "That's putting a criminal in jail. That's being a policeman."

The prosecution sought to portray Fuhrman's statements as a combination of macho braggadocio and fantasy designed to provide material for a fictional screenplay. Under cross-examination by prosecutor Christopher Darden, McKinny said she had made it clear to Fuhrman that her planned screenplay was to be a "dramatic fictional work based on reality."

Prompted by Darden's questions, McKinny said she provided Fuhrman with "scenarios" and then asked him how a police officer might respond.

"Is it fair to say that detective Fuhrman was helping you make up a story?" Darden asked. McKinny replied, "It is fair to say he was giving me information that helped me develop characters for a story."

Asked why she had not come forward immediately when Fuhrman testified under oath that he had not used the "N-word" in 10 years, the soft-spoken McKinny, who at times wept while on the stand, said she did not think that the tapes bore directly on Simpson's guilt or innocence.

"There was nothing to me that made me feel that Officer Fuhrman could have planted evidence in this case," McKinny testified.

Judge Ito has indicated he will first rule on the overall admissibility of the transcripts, then decide which, if any, of the individual statements he would allow. He did not indicate today when he would render a decision. CAPTION: Laura Hart McKinny testifies about interviews with Mark Fuhrman. (Photo ran in an earlier edition) CAPTION: Prosecutors Marcia Clark and Christopher Darden review transcripts of interviews of detective Mark Fuhrman taped by screenwriter Laura McKinny.