LOS ANGELES (CBSLA.com) — Los Angeles County Sheriff’s homicide detectives Thursday were investigating the death of a 2-year-old boy who was supposed to be under protective supervision.

Josue-Rey Maldonado, of Signal Hill, died Aug. 10 after county social workers allegedly left him with his mother, who was receiving court-ordered training to improve her parenting skills.

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Witnesses said Maldonado had bruising on his face the night before he died, the Los Angeles Times reported.

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The apparent cause of death was homicide, according to a Department of Children and Family Services report reviewed by the Times.

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The toddler’s three siblings were taken into protective custody.