The death of a teenager killed when a stone slab weighing about 650 pounds fell on him at a southern New Jersey business last weekend has been ruled an accident.

The Ocean County prosecutor's office announced its finding Tuesday.

Investigators concluded that 17-year-old Jared Marchiano, of Berkeley Township, was trespassing at Stone N' Counters South LLC when he accidentally dislodged the slab, which pinned him beneath its full weight. The business was closed when the accident occurred.

Authorities did not say if it's known how long Marchiano was trapped before a passing motorist spotted him early Saturday and called police. He was pronounced dead shortly after authorities arrived.

An autopsy determined that Marchiano died of asphyxiation.