Police say a 9-year-old Las Vegas girl died of a prescription drug overdose after her mother and aunt gave her oxycodone and other painkillers for an injury.

Las Vegas police said Thursday the women were both charged with murder after tests confirmed lethal levels of multiple drugs in the child's body.

The Clark County coroner says the child overdosed on hydrocodone and oxycodone, and also suffered from pneumonia.

Authorities say the mother and aunt gave her drugs that weren't prescribed to her to treat symptoms related to the unidentified injury before the girl's death in August.

Police say there were early indications that prescription drugs were involved and the subsequent investigation showed she'd been given the medication.