For years, people have blamed Heath Ledger’s intense journey into the mind of The Joker as probably cause for his ultimate downward spiral, but Heath’s sister says that is far from true.

“He wasn’t depressed about The Joker,” Kate Ledger said during a Q&A at the Tribeca Film Festival this weekend after attending a screening of the new documentary I Am Heath Ledger. “Honestly it was the absolute opposite. He had an amazing sense of humor, and I guess only his close family and friends really knew that. But he was having fun.”

The actor sadly died at the age of 28 due to a mix of drugs and alcohol. Kate and her sister Ashleigh say they were both shocked to hear the amount of rumors circling after their brother’s death.

“It was coming out that he was depressed and it was taking a toll, and we were going, ‘What?’” Ashleigh said. “Obviously he was such a prominent actor and everyone knew that side of him already… But we knew the photographer, the father. He was such a filmmaker. He was such a creator of everything.”

“Because he was really not a celebrity. In his eyes, he really wasn’t. We wanted that to come through,” Kate added.

I Am Heath Ledger has a limited theatrical release starting May 3 and will also air in a shortened form on cable channel Spike TV from May 17.