The mother of a 3-year-old girl who died in Brooklyn on Tuesday has been charged with manslaughter and assault after the Medical Examiner’s Office ruled the death a homicide, police officials said yesterday.

The mother of Kiana Rosado, Jessica Rosado, 18, was placed under arrest yesterday evening, police said. She was charged by police with manslaughter in the first and second degrees, criminally negligent homicide, and endangering the welfare of a child.

Rosado had blunt impact injuries to the torso and suffered lacerations to her liver and major blood vessels, a spokeswoman for the Medical Examiner, Ellen Borakove, said. She also had injuries at different stages of healing, Ms. Borakove said.

When paramedics came to the apartment on Tuesday morning, they found Rosado struggling to breathe. She was covered with bruises on her neck, back, and head, police said. A neighbor said Ms. Rosado told her that her daughter had fallen down and wouldn’t wake up. She later said that she had given her Benadryl to help her sleep.

Rosado was pronounced dead at Jamaica Hospital Medical Center in Queens later that morning.

Police sources disclosed yesterday that the girl’s mother had a history with the Administration for Children’s Services, involving her own mother. A spokeswoman for ACS declined to comment because of privacy laws. There was no previous case regarding Ms. Rosado and her daughter, police said.

Ms. Rosado’s boyfriend, Ruben Pagan, 23, with whose child she is seven months pregnant, is not thought to be involved with any abuse of the 3-year-old girl, police said. He was also charged with endangering the welfare of a child and possession of marijuana. Both were expected to be arraigned this morning.