Timothy J. Buzbee, charged in connection with a series of rapes in the Aspen Hill area, was found guilty yesterday of trespassing in an incident in November in which Buzbee followed a 9-year-old Bethesda girl home after dark and peered in the windows of her house.

At a hearing in Gaithersburg, District Court Judge Stanley Klavan sentenced Buzbee to 30 days in jail. Buzbee, who is awaiting trial on four counts of rape and lesser charges, has been jailed since Nov. 5. He was credited with time already served, then handcuffed and returned to the Montgomery County Detention Center.

Dressed in a blue pin-striped, three-piece suit, the 26-year-old land surveyor and father of two daughters sat impassively throughout the two-hour hearing as five witnesses, including the 9-year-old, took the stand.

Members of the plainsclothes team of Montgomery County Police that kept Buzbee under surveillance for two weeks before his arrest testified that they saw Buzbee sitting in a Toyota Tercel shortly before 6 p.m. on Nov. 4.

They said he was watching a girl crossing a parking lot in a shopping center near Bradley Boulevard in Chevy Chase. She was heading home from the Bethesda Library on a drizzly evening, carrying an armload of books and twirling an umbrella. She had recently moved to the area with her mother.

"I watched him Buzbee watch her," officer Robert D. Angelino testified. "As she got to the corner he rolled down his window . . . she continued down the street, he got out and looked down the street in the direction she was going."

The girl was met by a friend of her mother's in front of the house on Bradley Boulevard and went inside, police said.

Police officers then watched as Buzbee entered the yard and prowled outside the house for about eight minutes. He looked in windows on both sides of the house, explored the back yard and "made a move toward the front door," Angelino testified.

"I watched him peer into the window on the left side," Angelino continued. "One time he had to stand on his toes to look in. He ducked down real quick, exited the yard and went back to his car."

Buzbee was arrested the next day after leaving work in Gaithersburg.

Buzbee's lawyer, Reginald W. Bours, argued that strictly speaking, the prosecution had not proved that Buzbee had been trespassing and suggested that he could have been looking in windows for several reasons.

"What was he doing at the back of the house?" Judge Klavan asked Bours. "Thank you for the argument. I disagree. I find him guilty."