A Prince William County judge yesterday dismissed a sexual abuse charge against the adoptive father of a 14-year-old girl who prosecutors said had chronicled three years of sexual torment before she committed suicide last month.

Juvenile and Domestic Relations Chief Judge Raymond O. Kellam dismissed the charge of aggravated sexual battery against Paul J. Kauffman Jr., ruling that testimony about his daughter's final words accusing him of abusing her was not admissible as evidence.

" . . . The trustworthiness of someone who takes his or her own life is fatally flawed," said Kellam, noting that the girl, Kristi Kauffman, drank a soda bottle filled with vodka on April 1, the day she committed suicide.

"She was afflicted with a substance that is likely to cause her to make rash actions and rash statements," Kellam said.

Kauffman, a popular ninth-grader at Osbourn Park High School in Manassas who made the honor roll and was a standout on the soccer team, jumped in front of a freight train near the school after telling friends she was troubled by the years of abuse she had undergone.

Investigators said they later discovered a journal that detailed alleged actions by her adoptive father, who was then charged with sexual battery.

Kellam's ruling freeing the father came after testimony by Prince William police investigator John Urban, who said Kauffman told him that he had had numerous sexual encounters with his daughter.

Urban testified that Kauffman, a car salesman, told him that his involvement with his daughter began three years ago when they began to fondle each other while he was intoxicated and lying naked with Kristi on her bed.

The officer said Kauffman told him that after that, sometimes as often as four times a week, he would enter the girl's room at night. The father was charged in an incident, mentioned in Kristi's journal, that was alleged to have taken place March 10.

Commonwealth's Attorney Paul B. Ebert said he had planned to call Kristi Kauffman's friends as witnesses. Ebert said the friends would have testified that the girl told them moments before stepping in front of the train that she was distraught over being abused.

If necessary, the prosecutor said, he planned to introduce Kristi Kauffman's journal as evidence.

Kellam's ruling blocked that. The judge said that the friends' accounts -- and, presumably, the journal entries -- were hearsay, and could not be used to implicate Paul Kauffman.

Ebert said after the hearing that he agreed that Kauffman's statement to the police officer was not sufficient for the judge to find probable cause against him.

"Under Virginia law, there must be more than the testimony of the defendant to establish" a crime, the prosecutor said. "If we could have gotten any other little bit of evidence, in my judgment, we would have been all right."

Ebert said he may take the case directly to the county grand jury, which can consider cases that judges have not agreed to send them.

In court yesterday, Ebert argued that the friends' accounts of Kristi Kauffman's final words were acceptable because of a provision in Virginia law that allows hearsay accusations when they are made in a "dying declaration" -- a statement made in immediate expectation of death.

Kellam disagreed, saying that dying declarations are valid only in homicide cases.

He also rejected Ebert's request to have the testimony admitted because it gave insight into Kristi Kauffman's "state of mind" at the time of her death.