A DEA investigation into whether perscriptions for oxycodone and hydrocodone were obtained by Heath Ledger illegally before his death has been dropped. Earlier this week, it was revealed that Ledger's friend, Full House star Mary-Kate Olsen—pause for sad head-shaking—was demanding immunity from prosecution before she would speak to the DEA about the death and the actor's drug use. At the time, Olsen's lawyer Michael C Miller said his client had told the authorities all she knew and that she "does not know the source of the drugs Mr Ledger consumed." The DEA had obtained a subpoena that could have forced Olsen to speak out, but it is no longer valid because the case is being dropped. The case could still be revived if evidence of a crime emerged.