Washington, Aug 7 : Hollywood actor Heath Ledger's death investigation has been closed after prosecutors decided not to pursue a criminal case.
Ledger, who was found dead at his Soho apartment on January 22 accidentally, died of drug overdose.
The decision comes after actress Mary-Kate Olsen was demanding immunity before answering questions about the death of her close friend and his drug use, reports People magazine.
Reports claim she was the first person called by a masseuse who found the 28-year-old Dark Knight actor dead in his Manhattan apartment.
Since Ledger died of a cocktail of Oxycotin and Vicodin two powerful painkillers, officials wanted to find out the sources of the substances.