Olsen again proves elusive

Federal investigators want to question actress Mary-Kate Olsen about how Heath Ledger got two powerful painkillers that contributed to his accidental overdose death, but she’s not talking, a law enforcement official said Monday.

Olsen’s lawyer has twice refused requests to have her sit down with investigators probing the death of the scene-stealing star of “The Dark Knight” earlier this year in a Manhattan apartment, said the official, who spoke on condition of anonymity because the investigation has not been concluded.

The official confirmed a report that Olsen -- a close friend of Ledger who learned about the 28-year-old actor’s death in a frantic phone call from a masseuse -- wants a promise of immunity before she speaks to the Drug Enforcement Administration.

The activity demonstrates that federal authorities are still actively trying to figure out how Ledger got some of the drugs that killed him.