A Prince George's County judge dismissed charges yesterday against a former inmate of the Prince George's County jail, accused of taking part in the rape of a fellow inmate in 1981, after the alleged victim denied three times on the witness stand that he had ever been sexually assaulted.

Judge James M. Rea said that unless the alleged victim, Patrick M. Miles Jr., was willing to testify against the defendant, Clifton Earl Tucker Jr., he had no choice but to acquit Tucker of sexual offense charges.

The decision for acquittal came after the judge, in an unusual action in a Maryland court, ruled that parts of Miles' grand jury testimony should be read to the the trial jury. Grand jury proceedings ordinarily remain secret.

The judge said he based his ruling on a 67-year-old case in Iowa.

Assistant State's Attorney John P. McKenna requested that Miles' grand jury testimony be read because in it Miles said under oath that Tucker held him down while Miles was raped by a third inmate.

That same grand jury later indicted Tucker and the other inmate, Wallace (Bam Bam) Parker Jr., on charges of second degree sex offenses and assault with intent to commit rape. Parker is awaiting trial.

Frederick C. Cohen, the court reporter who had recorded Miles' grand jury testimony last November, was first called to read his record of those proceedings in front of Miles. The jury was sent out for that reading.

After Cohen finished, Miles denied--for the second time in the two-day trial--that he had been raped. The jurors were then called back in to hear Miles' grand jury testimony, after which Miles again took the witness stand and denied the rape a third time.

"Unless Mr. Miles is willing to sit up there and tell what happened to him, the state is helpless," prosecutor McKenna said. McKenna rested his case after calling just one witness, Cohen, the court reporter.

Defense attorney Michael John Miller called for and won dismissal of the case on the grounds that Miles had been the only witness to ever place Tucker at the scene of the incident.

Tucker is the first of 12 defendants charged in connection with sexual assaults at the jail to be acquitted of the charges.

The charges followed a series in The Washington Post that said that about a dozen sexual attacks a week occurred at the jail and detailed several such incidents. The incident involving Miles was not mentioned in that series, but Tucker and Parker, who prosecutors alleged actually raped Miles, were quoted in the series as saying they took part in separate sexual assaults on other men.

Tucker still faces trial on a charge of assault with intent to rape in a separate case that was mentioned in the series.

Following yesterday's dismissal, Tucker said, "It's my victory." Tucker is currently imprisoned at the Maryland Correctional Institution in Hagerstown on an armed robbery conviction.

Prosecutors maintained that Miles, who is serving time at the Maryland Correctional Training Center in Hagerstown, changed the story he originally told police and prosecutors because he feared retribution. An assistant prosecutor said it is unclear whether the county will bring charges against Miles for changing his story.