NEW YORK -- Philip Seymour Hoffman, who fiercely protected his private life, will be mourned behind closed doors.

A private funeral for the actor will be held Friday at the Church of St. Ignatius Loyola in Manhattan. It's the same church that hosted the funerals of Jacqueline Kennedy Onassis, Lena Horne and Aaliyah. About 400 people are expected to attend the service.

Hoffman, 46, was found dead Sunday of an apparent heroin overdose in his apartment. He had been open about a past that included addiction and rehab. He leaves behind his partner of 15 years, Mimi O'Donnell, and their three children.

More tests are needed to determine what exactly killed Hoffman, who was found with a syringe in his arm and what authorities said were dozens of packets of heroin in his apartment. Autopsy results were inconclusive, authorities said this week.

A larger memorial service is being planned for later this month. On Thursday evening, family and close friends gathered for a private wake at the Frank E. Campbell Funeral Home in Manhattan, which has orchestrated funerals for celebrities including Kennedy Onassis and James Cagney.

Among the mourners was Amy Adams, who co-starred with Hoffman in the films "Doubt" and "The Master." Other notables in attendance included Cate Blanchett, Joaquin Phoenix and Diane Sawyer.

Hoffman was nominated for Academy Awards four times and won the Oscar for best actor in 2006 for his portrayal of writer Truman Capote in "Capote." He also was nominated three times for a Tony Award.

Broadway honoured him Wednesday night by dimming its lights for a minute, a memorial common for renowned stage actors. Thespians also gathered that night for a vigil.