Soon after Heath Ledger died at age 28 in 2008, people and publications began to blame his penultimate role — the Joker in The Dark Knight — for his death, caused by a drug overdose. A new documentary about his life, titled I Am Heath Ledger, seeks to put those rumors to rest.

After a screening of the film at this year’s Tribeca Film Festival, EW and PEOPLE Editorial Director Jess Cagle sat down with the filmmakers, Derik Murray and Adrian Buitenhuis, along with Ledger’s friend, Matt Amato (also an executive producer on the doc), and two of his sisters, Kate Ledger and Ashleigh Bell. There, they discussed the misconceptions around their loved one’s death.

“Everything that came to light about the Joker, we were all so confused,” Kate said. She and Bell went on to call speculation that the role made their brother depressed “so not true.”

“Honestly, it was the absolute opposite,” Kate went on. “He had an amazing sense of humor, and I guess maybe only his close family and friends really knew that, but he was having fun. He wasn’t depressed about the Joker.”

Heath ended up winning a posthumous Oscar for his performance as the Dark Knight villain, a role he was universally praised for. “I kind of raised my eyebrow at the casting and thought, ‘Oh, I wonder how that will be,'” costar Gary Oldman previously told EW. “But any concerns that one may have had vanished when you got on the set with him. I did a couple of scenes with Heath in the first leg of the shoot in London. I called a friend and he said, ‘How’s Heath?’ I said, ‘He’s breathtaking. He’s going to be astounding.’ I could tell just working for five minutes with him.”

Earlier in the panel, Amato expressed that he was initially hesitant to ever do a film about his late friend but was attracted to this opportunity because of the chance it gave him and others to address misinformation about Heath’s life and death.

“I hope it’s an antidote to a lot of the gossip that exists in the world. And there’s some really terrible things about Heath out there,” he said. “I think one just came out, and I haven’t seen it and I never will, but I know it’s bad. And if we could provide an antidote in our culture to something like that, and I think everyone’s life should be celebrated. Your life, your life, my life, everybody’s life, should be celebrated. Heath is a celebrity and in the public eye, and I felt like some corrections needed to be made. But in terms of a film as a tribute, I think everybody deserves that. And I know Heath definitely felt that way about people.”

I Am Heath Ledger will air on Spike TV Wednesday, May 17 at 10 p.m. ET. It will then be released digitally and on DVD May 23. Watch the trailer above.