Mary-Kate Olsen Is Off the Hook

"Why did Heath Ledger's masseuse call Mary-Kate Olsen first?" is a question that has just secured its place on the grassy knoll of pop culture mysteries.

The Associated Press reports that federal prosecutors will not investigate how Heath obtained the prescriptions which contributed to his accidental overdose in January. Earlier this week, rumors circulated not only that an inquiry was on, but that MK -- a friend of the late Ledger -- was demanding immunity before she would discuss his death with law enforcement officials.

Heath was found dead on January 22, having overdosed on a variety of medications including painkillers, anti-anxiety meds, and sleeping pills. His body was discovered by a masseuse, who called Mary-Kate three times before dialing 911.

A lawyer for pint-sized mogul MK says his client told the feds she "does not know the source of the drugs Mr. Ledger consumed."

Do you think something fishy's afoot?