The case of the one-year-old boy who died in the care of his mother's boyfriend has been ruled a homicide by the New York City medical examiner.

The autopsy found that baby Richard Flood had rib fractures and injuries to his internal organs and eventually died from blunt force injury to his torso.

Police found the body of the toddler unconscious and unresponsive on the living room floor of the mother's Bronx apartment just before noon on Wednesday. The boy was taken to Montefiore Hospital where doctors pronounced him dead on arrival.

Police say the boy had bruises on his arms, apparent cigarette burns on each of his arms and a cast on his right leg from a previously broken bone.

The mother's boyfriend told police that the boy had fell after being questioned on Wednesday. No charges have been filed yet, but police are still investigating.