Law enforcement sources said Sunday that Oscar-winning actor Philip Seymour Hoffman, 46, was found dead in his Manhattan apartment of an apparent drug overdose. A needle was in the actor's left arm and investigators found two bags of what is believed to be heroin inside the apartment.

"He'd go quietly about his business with his children. I still remember the day he won the Oscar, him walking his kids to school, not long after. And people were giving him high fives," said one source whose daughter attended school with Hoffman's children. "It looked like it really meant something to him to have his neighbors saying congratulations. It's shocking, and I know everyone in the neighborhood is going to feel like they're missing a friend, like a friend has died."

Hoffman's break into Hollywood was a small role as Chris O'Donnell's classmate in the 1992 film "Scent of a Woman." A senior editor of US Weekly said "he just loved those deep, dense characters. That's where I think he found his true calling." Here are some of his best performances:

Happiness (1998): Hoffman was bold in choosing to play a peeping tom in Todd Solondz's drama about a timid neighbour Allen who has a taste for obscene phone calls.

Magnolia (1999): Hoffman played a male nurse who was devoted to a dying man in California's San Fernando Valley.

Capote (2005): Hoffman portrayed author Truman Capote as he researched the classic true crime book, In Cold Blood. The performance won him the best actor Oscar over another Heath Ledger in Brokeback Mountain.

Charlie Wilson's War (2007): Hoffman played the role of Gust Avrakotos and his partnership with Texas Congressman Charles Wilson in this biographical drama that earned him a nomination for an Academy Award for Best Supporting Actor.

Jack Goes Boating (2010): Hoffman's directorial debut, where he plays a shy limo driver with an unlikely dream. It's the story of an ordinary guy trying to improve himself and exudes Philip Seymour Hoffman.