Published: Aug 11, 2014 11:11 AM EDT

TAMPA, Fla. (AP) - Police say they've arrested a 24-year-old man who is accused of killing his girlfriend's 1-year-old son at a Tampa motel.
    
Austin Hamilton is charged with first-degree murder of Sincere Williams, who just turned 1. His mother told police she left the boy and his 6-year-old sibling with Hamilton on Saturday while she went to work.
    
Hamilton called 911 after the child began having trouble breathing. The boy was pronounced dead at a hospital.
    
Police say Hamilton told them the boy urinated as he was changing his diaper. Hamilton said he "lost control" and hit the boy with a leather belt. He says he tried to pick the boy up, but he fell and hit his head. The other child wasn't injured.
    
Hamilton is being held without bail.

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