Mary-Kate Olsen has avoided being served.

Law enforcement reps, speaking on condition of anonymity, are saying that the Drug Enforcement Administration has closed its investigation into how Heath Ledger obtained two of the prescription painkillers found in his system at the time of his sudden death on Jan. 22.

That aspect of the federal agency's inquiry was expected to involve Olsen, who via her attorney issued a statement Monday saying that she had "nothing whatsoever to do with the drugs found in Heath Ledger's home or his body, and does not know where he obtained them."

Sources confirmed she wasn't willing to talk to the Feds unless granted immunity for any possibly illegal activity, and a subpoena was reportedly headed her way.

Diana Wolozin, the masseuse, who discovered Ledger's body, used the Dark Knight star's cell phone to call Olsen three times (he had her on speed dial) before she called 911, prompting endless conspiracy theories as to what role—if any—the famous twin played.

It's still unclear whether Wolozin actually got a hold of Olsen because the actress has yet to confirm that a conversation took place.

(Originally published Aug. 6, 2008 at 5:13 p.m. PT.)