An autopsy shows that a 2-year-old New Jersey boy died as a result of decapitation.

Authorities say Zahree Thomas died after his mother decapitated him early Wednesday at their Camden rowhouse. Autopsy results released Thursday on mother Chevonne Thomas showed she died of a knife wound to the neck.

Thomas lost custody of Zahree in 2010 after she admitted smoking marijuana and PCP and leaving the boy alone in a car.

Authorities say there are indications Thomas might still have been using PCP and marijuana.

She regained custody of Zahree in April.

The case is raising questions about New Jersey's child welfare agency, which has been under federal oversight for nearly a decade.

A spokeswoman says the agency is still investigating. It said Wednesday that staffers visited the family regularly.