Shirelle Winzor, a 15-year-old Northwest Washington girl, was found stabbed to death early yesterday in an abandoned car on a parking lot at Ninth and M streets NW, D.C. police reported.

Police said they have no motive in the slaying and they are looking for an unidentified man last seen with the girl shortly before her body was discovered by a passerby about 5 a.m.

"She was a good-hearted child," Shirelle's mother, Willette Street, said yesterday as she sat in a wheelchair in the kitchen of her town house in the Golden Rule housing complex near North Capitol and K streets NW.

Street said she last saw her daughter early Thursday night. Michelle Brockenberry, a friend, said she saw Shirelle about 2 a.m. at Eighth and M streets NW in the company of Shirelle's boyfriend. She said another friend saw Shirelle after 2 a.m., and the 15-year-old seemed to be depressed.

One person who talked with police but asked not to be identified said he saw the girl with an unidentified man shortly before 5 a.m. near an abandoned car in a vacant lot across from where her body was found. The witness said the two left that lot.

Winzor's partially clothed body was found in the back of a two-door, blue and white abandoned car on a lot at 917 M St. NW, police said. She had been stabbed once in the back, according to the D.C. medical examiner's office.

Yesterday, friends and relatives who gathered at Street's home said they were shocked by the killing.

"Shirelle was a child who had a lot of love to give and needed a lot of love," said Sister Diane Rocke, a Catholic nun who has known Shirelle five years.

"She was spunky," Rocke said. "I remember she was in this Miss Northwest pageant we had five years ago.The day of the pageant she fell on her skates and scrapped her face. She had a bad scar, but she went ahead anyway."

"That's her trophy she won" in the pageant for selling the most tickets, Street interjected, pointing to a small trophy on top of the refrigerator.

Street said Shirelle, who dropped out of Terrell Junior High School in eighth grade, often got into fights. "When she started school, the kids used to make her run to school and run back. One kid told her the only way to keep them from chasing her so much was to fight back. She started to fighting and I never could stop her from fighting."

Her mother said Shirelle told her that the kids used to tease her because Street was in a wheelchair. "I tried to tell her about the boxers and how they find the weak point and win the fight. She said, 'Mama, I can't stop fighting because I get tired of them calling you names.'"

"She was very close to Mrs. Street," said Roche, who works with a senior citizens' group in the Sursum Corda public housing project nearby.

Shirelle's cousin said the family became concerned when they didn't hear from Shirelle by early morning. "It wasn't like her to stay away that long without calling," the cousin said.

Weeping softly, Street searched her wallet to find a picture of her daughter. "She had been talking about getting another picture made," she said, flashing the girl's sixth-grade graduation picture.

"I lost my daughter five years ago," said Street, her voice breaking and tears rolling down her face. "Now Shirelle is gone."

She was the ninth person aged 17 or younger to be killed this year in the District of Columbia. All of the eight previous cases have been closed by police.