Heath Ledger's father reveals the last thing his son told the family

"Katie, Katie I'll be fine," were actor Heath Ledger's last words, according to his father, Kim.

Kim Ledger revealed the his son's final conversation with his family to Australian news website, news.com.au.

Heath's sister Katie apparently told him not to mix prescriptions, saying, "You can't mix drugs that you don't know anything about."

The next night, Ledger's body was found in his apartment in New York City. He was 28 and a celebrated actor with the promise of even more success.

Heath Ledger through the years:

According to a toxicology report, Ledger died from a combination of prescription drugs. The medical examiner ruled his death accidental.

Kim told news.com.au his son wasn't an addict but just made a mistake mixing drugs.

Ledger's work and travel schedule reportedly put a lot of stress on him. Kim said: "He was a young guy that traveled all the time for work. ... He was trying to work and travel and do everything in a short space of time."

Since his son's death, Kim has been trying to raise awareness about the dangers of prescription drugs.

Ledger left behind a then 2-year-old daughter, Matilda, he had with actress Michelle Williams.

Photos of Ledger, Williams and Matilda: