A 15-year-old girl who alleges she was raped by a Montgomery County police officer in a basement room of a Bethesda elementary school last February testified yesterday that the dirt-floored room is frequently used by "everyone in the area" for "getting high" and "partying."

"That's where everyone goes," the girl told the jury hearing the case in the courtroom of Montgomery County Circuit Court Judge Joseph M. Mathias. The girl described the basement room at the Brookmont Elementary School, 4800 Sangamore Rd., as being haphazardly furnished with chairs and cushions and containing "wax dripping," candles, beer cans, coke bottles and empty snack food bags.

The girl was described by the defense lawyer as a "snitch" for the policeman who allegedly raped her. She was showing the room to the officer when the rape occurred, she testified.

The hideaway was called "the partying room," she testified. Access was gained by squeezing through a small hole in a wall on one side of the school.

The hole, covered by a metal grate, measured 36 by 30 inches, she said. She testified that she had attended parties in the room "several times" and was showing it to the policeman, Joseph Ezekial Baltimore, 32, so he could close it up so that "none of my good friends (would) get busted."

Baltimore, who is charged with two counts of rape and one count of sexual assault, in connection with the February 13 incident has pleaded innocent.

The girl testified that she had drunk four beers and two rum-Cokes early in the evening before she led the officer through two adjoining basement rooms to the "partying" room.

She testified that the only illumination came from the policeman's flashlight, which she was holding. After showing Baltimore the room she turned to go "when he puts his hand on my hips," forced her down on an orange cushion, and raped her, she testified.

After the alleged rape, the girl testified she "jumped up" and led the way back to the police cruiser parked nearby. Sleeping in the back of it, she testified, was a teen-age friend. Baltimore drove the two of them to the home of the sleeping girl, whose sisters called police, she said.

"I was scared, because, you know, he could have killed me if he had wanted to" with his police service revolver, said the girl, who cried several times during the testimony.

Defense attorney Courtland K. Townsend claimed in opening arguments that Baltimore had been asked to drive the two young girls home by another Montgomery County police officer.

Baltimore, who had been told he would soon be transferred to an undercover assignment was trying to develop "snitches" of his own, Townsend claimed.

The girl testified that she had asked Baltimore to drive her to the school rather than drive her home. She testified that during the ride she had sat in the front of the cruiser with Baltimore, worn his police hat, and played with his night stick.