Pint-size actress Mary-Kate Olsen has refused to be interviewed by federal investigators probing the accidental drug death of her close friend Heath Ledger unless she receives immunity from prosecution, The Post has learned. The actress' lawyer has repeatedly rebuffed attempts by the feds to question Olsen, who was the first person called after her masseuse discovered Ledger's body in his SoHo apartment in January. More... Discount Magazine Subscriptions - Discount Cigarettes & Tobacco - Nutty News Marketplace - Black Hound New York