Heath Ledger's Sister Warned Him Not To Mix Pills The Night Before His Death

Heath Ledger brushed off warnings from his family about his drug use the night before his tragic death. The late actor's father, Kim Ledger, revealed that his daughter warned her brother about mixing prescription pills.

"You can't mix drugs that you don't know anything about," Kim told Australia's News.com.au of his daughter's advice.

Ledger responded, "Katie, Katie, I'll be fine."

The actor was found dead in his Manhattan apartment in January 2008.

He was only 28 years old at the time and left behind daughter Matilda, now 10, with ex-girlfriend Michelle Williams.

A toxicology report showed oxycodone, temazepam, diazepam, hydrocodone, alprazolam and doxylamine was found in his system.

His death was ruled accidental.

"It just put his whole system to sleep I guess," Kim said. "It was a one-off thing. That's what killed us, because he was warned by his sister the night before: 'You shouldn't mix what you're taking for pneumonia with your Ambien.'"

Kim believes his late son's work schedule played a role in his drug use.

"He was a young guy that traveled all the time for work," he said. "Even as a 2-year-old, he hardly ever slept. He was trying to work and travel and do everything in a short space of time. Heath mixed a couple of drugs together with sleeping tablets and he's gone forever. That's something we just have to deal with."

Kim is hoping to save others by being an advocate for drug awareness.