A 13-year-old boy whom police allege severely beat a two-year-old girl at a baby sitter's home Friday is now in custody at the Salt Lake Valley Juvenile Detention Center.

The boy was arrested about 7:30 p.m. Monday, Salt Lake County deputy sheriff Peggy Faulkner said. He is charged with one count of aggravated assault, a second-degree felony.The beating occurred Friday afternoon at the Sunnyvale Apartments, 740 W. 3940 South, where Jessica Maxwell has been going to stay with a baby sitter for the past three months. The baby sitter is also the girl's aunt and the older sister of the suspect.

The girl suffered severe bruises to her face, back, arms, liver and spleen, but she is expected to be fully recovered in about about a month, her mother, Aimee Maxwell, 19, said. Jessica was released from Primary Children's Medical Center Monday.

Mother and daughter are happy to be home, Aimee Maxwell said Tuesday morning, adding that she was glad to know the boy was in custody.

She said she planned to attend his juvenile court hearing.