Smith, the mother's boyfriend, is charged with murder and assault.
Police had arrived on the scene at around 11 a.m. Wednesday on East 232nd Street in the Williamsbridge section.
Fludd was found unconscious on the ground of the third floor apartment.
He was rushed to Montefiore Hospital where he was pronounced dead.
The cause of death was blunt impact injury to the torso, with rib fractures and internal injuries.
The child had a cast on his right leg and burns on both arms at the time of the incident, and the source says that the burns are consistent with what you would find from a cigarette burn.
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