Heath Ledger drug investigation 'dropped'

Heath Ledger died of an accidental overdose in January. Photo / AP

US prosecutors investigating how Heath Ledger obtained drugs that contributed to his accidental overdose in January have decided not to pursue a criminal case.

After Ledger - who had a two-year-old daughter with former fiancee Michelle Williams - died of accidental prescription drugs overdose in January, officials wanted to determine where he had obtained powerful painkillers Oxycontin and Vicodin - two drugs for which he had no prescription.

Despite reports Heath's close friend Mary-Kate Olsen - who was subpoenaed by a federal grand jury on April 23 - would be forced to involve herself in the investigation, the probe has now been closed without the subpoena being enforced.

When Mary-Kate - who was the first person Heath's masseuse called after she found him dead in his New York apartment - was issued with the subpoena, her attorney began negotiating with authorities, and was said to be trying to get the 22-year-old star immunity from prosecution before she would testify in the case.

He released a statement saying: "Ms. Olsen had nothing to do with any drugs found and has already provided relevant information for the investigation."

A coroner's report showed Heath died of an accidental overdose of prescription drugs for pain, anxiety and sleep.

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