Mystery Lingers Over Heath Ledger's Drugs Death On What Would Have Been Tormented Joker Actor's 46th Birthday: How Mary Kate-Olsen REFUSED to Cooperate With Cops Probing How He Got Hold of Deadly Pills Stash

Seventeen years have passed since actor Heath Ledger was discovered unresponsive at his Manhattan loft by his housekeeper and massage therapist, but the mystery lingers over his death and how he secured the cocktail of pills that caused his demise.

RadarOnline.com can reveal how Ledger's connection to former child star Mary-Kate Olsen muddied his death investigation as the actor would have celebrated his 46th birthday on April 4.

When Ledger's housekeeper, Teresa Solomon, and massage therapist, Diana Wolozin, stumbled upon the devastating scene around 3 PM on January 22, 2008, Wolozin's first call was not to police but instead to Olsen.

Then-21-year-old Olsen, who was in Los Angeles at the time, then called on her private security to go to Ledger's apartment.

After dialing Olsen, Wolozin finally called 911 and told the operator the 28-year-old Dark Knight star was "not breathing."

Autopsy results revealed the 10 Things I Hate About You star's cause of death was "the result of acute intoxication by the combined effects of oxycodone, hydrocodone, diazepam, temazepam, alprazolam and doxylamine."

The Office of Chief Medical Examiner of the City of New York's report added: "We have concluded that the manner of death is accident(al), resulting from the abuse of prescribed medications."

Given that Olsen was phoned by Ledger's staff before police, investigators wanted to question her as part of their probe, but she mysteriously refused.

On two occasions Olsen told Drug Enforcement Administration officers she would only speak about Ledger's death if she was granted immunity from future prosecution, according to a report from The Independent at the time.

Her attorney, Michael C Miller, also refused access to his client without an immunity guarantee protecting her "constitutional rights."

While Olsen's initial reaction to Wolozin's phone call sent off red flags for Ledger's fans, Miller insisted the actress had "nothing whatsoever to do with the drugs found in Ledger's home or his body."

Miller further claimed the Full House star had no knowledge of how Ledger acquired the prescription pills.

He added: "Regarding the government's investigation, at Ms Olsen's request, we have provided the government with relevant information including facts in the chronology of events surrounding Mr Ledger's death and the fact that Ms Olsen does not know the source of the drugs Mr. Ledger consumed."

Despite Miller's statement, rumors about Olsen's potential involvement swirled – and she was even rumored to be in a secret relationship with Ledger at the time of his death.