Mary-Kate Olsen has officially been subpoenaed by the DEA to answer questions about Heath Ledgers death.

For some reason, the authorities believe that Mary-Kate has some information about the drug cocktail that killed "The Dark Knight" actor.

Olsen claims to know nothing.

"Access Hollywood" broke the news about the subpoena on Tuesday night, but did not report a timeline for when Olsen might be called to testify.

Five different medications were found in Ledger's body at the time of his death, three of which he'd gotten from doctors in Texas and Los Angeles.

Officials are trying to determine how he got the OxyContin and Vicodin found in his apartment without a legal prescription.