An AIDS activist who has AIDS himself was sentenced yesterday to 25 years in prison, the maximum, for sexually assaulting a 9-year-old girl who was visiting his Frederick, Md., home two years ago.

Circuit Court Judge G. Edward Dwyer said that the crime, along with Lloyd Eugene Biggus's two previous convictions for molesting and assaulting children, left him little choice but to impose the maximum sentence.

"This is not a case for leniency," Dwyer said. "You are what is known, for lack of a better word, as a sexual predator." Biggus, 40, was found guilty in July of first- and second-degree sexual assault and second-degree sexual offense.

Frederick County State's Attorney Scott Rolle, who prosecuted the case, argued that only the maximum term "will guarantee Mr. Biggus will not do this again."

"This is essentially a life sentence," Rolle said afterward, noting that Biggus has "full-blown AIDS" and "his days are numbered."

The mother of the girl Biggus sexually assaulted declined to comment on the sentence but told reporters that the child had tested negative for the virus that causes AIDS.

Biggus himself decried his prosecution as "a farce, a mockery of justice." Biggus accused prosecutors of "conspiracy . . . prosecutorial misconduct . . . and witness tampering."

Although he denied the charges, Biggus acknowledged that the prosecution's statements about "my medical history" are true.

AIDS activists who worked with Biggus have said that publicity about the case had hurt their cause.

"We lost one grant and had others delayed because of it," said Stephanie Schwartzbeck, president of the People With Aids Committee of Maryland, a Frederick-based AIDS education and support group. Schwartzbeck said Biggus helped her start the group in 1997 and resigned soon after his arrest.

The girl testified in court during the trial, describing the September 1997 incident, which occurred shortly after Biggus had completed probation for a previous offense. Biggus had served eight years of a 10-year sentence for a 1987 assault on a 13-year-old boy he threatened with a carpet knife, according to court documents. His first sexual assault conviction, in 1980, involved a young girl, said Rolle, who described the details of the previous assaults.

"He had a modus operandi for sexually assaulting children," Rolle said. "He uses children time and again."