Lee Sun-kyun, a South Korean actor of the Oscar-winning film "Parasite," was found dead, Yonhap news agency reported on Wednesday, citing police.
Lee had been under investigation amid an ongoing government crackdown on illegal drug use.
Lee was found unconscious next to charcoal briquettes inside a car at a park in Seoul on Wednesday morning, after his wife reported to police that Lee had left home and she had found what appeared to be a suicide note, Yonhap said.
Seoul's Jongno police station did not immediately respond to phone calls.
South Korea has tough drug laws, and drug crimes are typically punishable by at least six months in prison or up to 14 years for repeat offenders and dealers.
Lee had been questioned three times by police, including for 19 hours over the weekend. The actor had said he was tricked into taking drugs by a bar hostess who then tried to blackmail him, Yonhap reported.
Born in 1975, Lee starred as the patriarch of a rich family in director Bong Jun Ho's "Parasite," which won the Palme d'Or at the 2019 Cannes Film Festival as well as four Oscars, including best picture.
Lee also played leading roles in South Korean movies including the 2012 thriller "Helpless" and 2014's "All About My Wife," among others.
Lee had the lead role in Apple TV+'s first Korean-language original series, which rolled out in 2021. "Dr. Brain," a six-episode sci-fi thriller, was about a cold-hearted neurologist, Koh Se-won, who tries to find clues to a mysterious family accident through brain experiments.