The U.S. Attorney's Office closed its investigation into Heath Ledger's accidental overdose death , PEOPLE reports.

U.S. Attorney's Office closes its investigation into Heath Ledger's accidental overdose death

The probe was closed without any charges being filed.

Mary Kate Olsen, 22, was subpoenaed by a federal grand jury on April 23, but her attorney had been in negotiations with federal authorities since then, the source says.

Olsen had wanted immunity before testifying. Olsen's attorney released a statement saying the actress "had nothing to do" with Ledger's drugs and had already provided "relevant information" to investigators.

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