A 12-year-old Northeast boy was charged with murder yesterday in connection with Monday's beating death of a 2-year-old girl left in his care while the girl's foster mother was away from her 14th Street apartment, D.C. police said.

The youth, whose name was not released because of his age, was charged after the investigators obtained a D.C. Superior Court juvenile custody order about 1 p.m., Sgt. Joseph Gentile, a police spokesman, said.

An autopsy performed Tuesday revealed that Mykeeda Asheya Hampton, of 2500 14th St. NE, died of "blunt force injuries" to the head, stomach and back. Sources said the child had been the victim of a "severe beating" and had old scars and bruises that could not be attributed to the fatal beating.

Mykeeda, a foster child of Geraldine Stevenson, was found unconscious in Stevenson's second-floor apartment by an unidentified adult relative shortly before 5 p.m. Monday, according to police. An ambulance was summoned by the adult, they said, and the girl was pronounced dead at 5:52 p.m. at Children's Hospital. Sources said the child and Stevenson's three other foster daughters were left with the youth at 9 a.m. Monday while Stevenson had her car repaired and visited her boyfriend. They said the youth told investigators that he became angry and used his hands to strike Mykeeda in the chest after the girl urinated on him.

Stevenson, licensed for foster care by the D.C. Department of Human Services, is in her forties and has four natural sons, three of whom live with her, sources said. They said she also cares for 5-year-old twins and an 18-month-old under the city's foster program.

One source said the beating apparently occurred in the "heat of passion," when the youth "got {angry} when she urinated on his hand."

"I don't think he meant to do it," the source said. "He just had a temper tantrum like little kids do. The sad thing is a boy that little having so much responsibility; he got frustrated. He thinks he was in charge of the four children and he had to spank them and all to keep them quiet."

Human Services Department officials said Tuesday that there had been no previously reported incidents of abuse in the foster home. Stevenson resigned a job as a procurement clerk at the Bureau of Indian Affairs in May after 16 years there to become a full-time foster parent, and sources said she had cared for Mykeeda for about a month before the girl's death.

Charles Siegel, a Human Services spokesman, said in a Tuesday interview that the agency has strict rules requiring that only baby sitters approved by the city may provide unsupervised care for foster children. Staff writer Victoria Churchville contributed to this report.