2008-08-08 09:12:02 - The US Attorney's Office official investigation into Heath Ledger's death of an accidental prescription drugs overdose in January has been closed without any charges being filed.

The US Attorney's Office official investigation into Heath Ledger's death has been closed without any charges being filed. After Heath - 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.