FILE: Comedian Robin Williams attends The Comedy Awards 2012 at Hammerstein Ballroom on April 28, 2012 in New York City. (Photo by Theo Wargo/Getty Images)
Robin Williams speaks onstage during the 38th AFI Life Achievement Award honoring Mike Nichols held at Sony Pictures Studios on June 10, 2010 in Culver City, California.
In this handout image provided by Disney, actor Robin Williams (C) is recognized by Bob Iger, CEO of Walt Disney Co.,and Mickey Mouse for Williams' work in 'Aladdin,' 'Good Morning, Vietnam' and 'Dead Poets Society' in a presentation announcing the D23 Expo September 10, 2009 in Anaheim, California. This fall, Williams stars with John Travolta in Walt Disney Films' 'Old Dogs.'
Actor Robin Williams walks the red carpet at the premiere of 'Night At The Museum:Battle Of The Smithsonian' at the National Air and Space Museum on May 14, 2009 in Washington, DC.
A U.S. soldier poses with Robin Williams after a United Service Organizations show at the US embassy, Kabul, Afghanistan in 2010.
Robin Williams accepts the Favorite Scene Stealing Guest Star award during the 35th Annual People's Choice Awards held at the Shrine Auditorium on January 7, 2009 in Los Angeles, California.
Actor Robin Williams (L) and host Ryan Seacrest speak onstage during the taping of Idol Gives Back held at the Kodak Theatre on April 6, 2008 in Hollywood, California. Idol Gives Back will air April 9, 2008 (7:30-10:00 PM ET/PT) on FOX.
Actor Robin Williams and members of the U.S. Navy attend Stand Up For Heroes: A Benefit For The Bob Woodruff Family Fund at Town Hall on November 07, 2007 in New York City.
Robin Williams (right) and actor Billy Crystal in 2006.
Robin Williams (right) with his daughter Zelda in 2006.
Actor Robin Williams gets slimed onstage at the 19th Annual Kid's Choice Awards held at UCLA's Pauley Pavilion on April 1, 2006 in Westwood, California.
Robin Williams with his snowboard at the Celebrity Sports Invitational fundraising event at the Sunshine ski resort in Banff, Canada in 2005.
Actor Robin Williams poses with his award as recipient of the Cecil B. DeMille Award during the 62nd Annual Golden Globe Awards at the Beverly Hilton Hotel January 16, 2005 in Beverly Hills, California.
In this picture released by the U.S. Air Force, actor Robin Williams gives his autograph to Senior Airman Cutis Netherton of the 386th Expeditionary Security Forces Squadron Monday, Dec. 13, 2004 at an unspecified forward-deployed location in Southwest Asia, the name given by the military to refer to the region that includes Iraq and Kuwait
In this US Army handout released on December 15, 2004 comedian and actor Robin Williams visits troops as part of a USO show to boost morale at Camp Victory in Iraq.
Actor Robin Williams appears on 'The Tonight Show with Jay Leno' at the NBC Studios on October 14, 2004 in Burbank, California.
Robin Williams performs at the Andre Agassi Charitable Foundation's Grand Slam for Children in Las Vegas in 2004.
Robin Williams entertains the troops during the United Service Organizations (USO) tour at Baghdad International Airport in December 2003.
Robin Williams performs on stage at 72nd Academy Awards.
Robin Williams (left) and his wife Marsha in 2000.
Robin Williams holds up his Oscar for Best Supporting Actor in 1998.
Robin Williams performing during a standup comedy routine in 1996.