An Arizona mother is in jail after police said she went to work and left her 1-year-old son alone in their apartment, where he was found dead 10 hours later.

According to court documents obtained by KTVK, Donielle Joyce King, 32, of Phoenix, was arrested and charged with child abuse after first responders found the boy unresponsive Tuesday afternoon.

King told investigators that she left the baby at home about 6:20 a.m. Tuesday before dropping off her other children at day care and going to work, the probable cause statement said. She claimed the baby could not go to day care because he "had open sores," court documents said. She also reportedly told investigators that a friend was supposed to babysit but never showed up.

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King said she came back home at 4:15 p.m. and found the baby unresponsive on a mattress, investigators said. She said she performed CPR on the child as her daughter called 911, court documents said.

The baby, who reportedly had several bruises, was pronounced dead about 4:47 p.m., court documents said.

King is being held on a $50,000 bond.

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