California attorney general Jerry Brown's office said on Friday that records of the prescription in the name of the former teenage heart throb were found during an investigation of the ring that illegally obtained prescription pads and used the stolen identities of doctors to fill them out.

"Corey Haim's death is yet another tragedy linked to the growing problem of prescription drug abuse," Brown said in a written statement.

"This problem is increasingly linked to criminal organisations, like the illegal and massive prescription drug ring under investigation."

Los Angeles County coroner's officials, however, said they have not yet determined what killed 38-year-old Haim on Wednesday.

State law enforcement authorities said they were investigating the drug ring and how Haim, who battled addiction for years, obtained the prescription.

One source said Haim may have been doctor shopping.

Assistant chief coroner Ed Winter said four prescription drug bottles bearing the actor's name were found in the apartment where he collapsed, but all those drugs had been provided by a doctor who had been treating the actor.

The coroner's office has declined to state what medications were discovered, but said no illegal drugs were found.

Winter said no determination had been made about Haim's cause of death, and toxicology tests would not be available for at least a month.