An autopsy concludes that head injuries killed a 9-year-old boy who police say was fatally beaten over a missing piece of birthday cake.

The Office of the Chief Medical Examiner for the District of Columbia called Jack Garcia's death a homicide.

The findings came Tuesday, one month after the boy died at a Washington hospital. His mother, her boyfriend and her brother are charged with fatally abusing him at their Hagerstown home June 30.

The brother told police he handcuffed Jack and the boyfriend beat him unconscious to punish him for stealing. Police say Jack's mother allowed the abuse and denied him treatment for several hours by sending away an ambulance that her brother had called.

She has pleaded not guilty to the charges. The others haven't entered pleas.