American stage and screen star Philip Seymour Hoffman – who won the Academy Award for Best Actor in 2006 for his portrayal of author Truman Capote – was found dead in his New York City apartment Sunday morning.

According to The New York Times, investigators “found a syringe in his arm and an envelope containing what is believed to be heroin.”

“It’s pretty apparent that it was an overdose,” a source told the paper. “The syringe was in his arm.”

Hoffman, 46, had been a prolific performer for the last two-and-a-half decades – receiving four Oscar nominations (including his 2006 victory) as well as three Tony Award nominations. Among his best known films? Scent of a Woman (1992), Twister (1996), The Big Lebowski (1998), The Talented Mr. Ripley (1999), Almost Famous (2000), Charlie Wilson’s War (2007) and Moneyball (2011).

In 2012, he portrayed Willy Loman in a Broadway production of Arthur Miller’s Death of a Salesman, winning his third Tony nomination.

Hoffman was scheduled to be in Atlanta, Georgia next week to continue filming on Mockingjay, the third installment of the critically and commercially successful Hunger Games series.

It’s unclear how his untimely passing will impact production of the film.

After struggling with drug use early in his career, Hoffman got clean in the early 1990s and stayed that way until last spring – when he checked himself into rehab in May for heroin abuse.

“It was anything I could get my hands on … I liked it all,” he said of his addiction in a 2006 interview with 60 Minutes.

Hoffman leaves behind his longtime girlfriend, costume designer Mimi O’Donnell, and three children – a 10-year-old son, 7-year-old daughter and five-year-old daughter.