Rocco's body was found May 1 by a friend at Rocco's home in North Hills, said his wife, Lisa, who was in Prague, Czech Republic, at the time.
A Los Angeles County coroner's office spokesman said there were no signs of trauma and no reason to believe there was foul play. Determination of the cause of death is pending further tests.
The adopted son of character actor Alex Rocco -- he played gangster Moe Greene in "The Godfather" -- Rocco made his feature film directorial debut with "Scenes From the Goldmine," a 1987 drama about the L.A. rock music scene that he also co-wrote.
His next film was "Dream a Little Dream," a 1989 body-switching comedy with Jason Robards, Piper Laurie, Corey Feldman and Meredith Salenger.
Rocco's 1992 film "Where the Day Takes You" spurred New York Times film critic Janet Maslin to write that "Rocco's name can be added to the list of formidable new talent."
A gritty tale of young runaways living on the streets of Hollywood, the film had a cast that included Kyle MacLachlan, Dermot Mulroney, Sean Astin, Lara Flynn Boyle, Will Smith and Ricki Lake.
"Murder in the First" (1995), starring Kevin Bacon, Christian Slater and Gary Oldman, is the true-story-inspired tale of an Alcatraz prisoner who was driven to madness during three years of brutal solitary confinement for an attempted escape and was then tried for murdering a fellow inmate soon after his release from solitary.
Among Rocco's other credits: He was an executive producer on "Take" (2007), and he co-wrote the story for "The Jacket"( 2005), for which he also was a co-producer.
Rocco was born in North Hollywood on June 19, 1962, to Harvey King and Sandi Garrett. He took the name Rocco when his mother later married the actor.
Rocco became a production assistant on "The Stunt Man," a 1980 film directed by Richard Rush, who became a mentor. Rocco later became a director trainee at Warner Bros. Television.
"Marc was a storyteller, a very gifted movie director, and an artist, above all," Rush said in a statement. "His death is a loss to us, but happily his artistic legacy lives on."
In addition to his wife of 17 years, Rocco is survived by his brother, Lucien; his sister, Jennifer; and his father, Alex.
A private memorial service for friends will be held Saturday. Instead of flowers, the family requests that donations be made to Rocco's memorial fund.
Information about the memorial service and fund may be obtained by e-mailing firstname.lastname@example.org or calling (888) 999-5070.