Subpoena For Mary-Kate Olsen Signed And Ready To Be Served In Heath Ledger Drug Probe

August 6, 2008 9:56 p.m. EST

Los Angeles, CA (CNS) - Mary-Kate Olsen is about to be served anytime soon. A federal law-enforcement source has confirmed that a subpoena for the star has been signed and just waiting to be enforced.

Just days after issuing a formal statement denying her involvement with Heath Ledger's drug probe, a subpoena with Olsen's name on it has been confirmed to exist.

The source tells E! news, "It was dated and signed on April 23, but it has not been enforced yet."

"We are still in negotiations. There are still negotiations with Mary-Kate's lawyer and also with our U.S. Attorney's Office, the prosecutors."

The legal order is for the young showbiz veteran's cooperation with the investigation of how Heath Ledger obtained medications without prescription, ultimately leading to his death in January.

Olsen, 22, will be required to face a grand jury and answer questions if the subpoena pushes through.

It was reported earlier this week that the famous twin refuses to cooperate until she's given immunity from prosecution. However, her lawyer issued a statement saying they have given the officials all the "relevant information" they need for the case.