Los Angeles County Assistant Chief Coroner Ed Winter tells E! News that the death of the Inception star's 36-year-old sibling, Dan Gordon-Levitt, may have been drug-related.
"It was initially reported to us as a possible overdose," says Winter. "There were two friends present and one of them also was taken to the hospital."
Winter reveals that Dan was pronounced dead at the scene on Monday at 3:58 a.m. in Los Angeles.
An autopsy has been performed, but, according to Winter, the final cause of death won't be released until toxicology tests are completed.
Dan, or "Burning Dan" as his friends called him, was a practicing fire performer who taught "flow" classes through his company Flow Arts in Hollywood.
On his Flow Arts website, Dan's partner "TeaFaerie" writes that she is a self-proclaimed "semi-professional trip sitter," which refers to someone who watches over people while they participate in psychedelic drug "trips."
On his personal blog, Dan had recently trumpeted his history of good health: "I've never had a cavity. I don't get sick. I'm not allergic to anything."
Yesterday, Joseph announced Dan's death via Twitter, writing, "My super hero brother @burningdan 1974-2010."