Corey Haim

California investigators have linked a drug prescription belonging to the late Corey Haim to a "massive" illegal prescription drug ring, state Attorney General Jerry Brown said.

"Corey Haim's death is yet another tragedy linked to the growing problem of prescription drug abuse," Brown said in a statement. "This problem is increasingly linked to criminal organizations, like the illegal and massive prescription drug ring under investigation. It's a serious public health problem."

Corey Haim's mother: He died of an enlarged heart, fluid in lungs

There was no evidence Haim was aware of the ring, which used stolen doctor indentities to order prescription drug pads from vendors, according to People. The pads were then sold directly to prescription drug addicts or to people paid to fill the prescription and sell the drugs, according to investigators.

Haim's prescription was found during an investigation of fraudulent prescription pads ordered from a San Diego vendor. The investigation has so far uncovered more than 4,500 unauthorized prescriptions linked to the Southern California fraud ring, authorities said.

Haim died on March 10 at the age of 38. The coroner has not yet released an official cause of death, but the Lost Boys actor's mother has said her son died of an enlarged heart and had fluid in his lungs.