Now Playing: Family Friend of Teen Who Killed Friend Was in Disbelief

Now Playing: Teens Charged as Adults for Murdering Best Friend

Now Playing: Teen Admits to Stabbing Best Friend to Death

Now Playing: Best Friends Last to See Teen Who Goes Missing

Now Playing: Missing Teen's Friend Has Nervous Breakdown

Now Playing: Police Suspect Missing Teen's Friends of Hiding Something

Now Playing: Robin Williams: A Look Back at the Actor's Life

Now Playing: Barbara Walters Remembers Robin Williams

Now Playing: Robin Williams' Battle With Depression, While Bringing Others Joy

Now Playing: The Many Faces and Voices of Robin Williams

Now Playing: Robin Williams' Hometown San Francisco Mourns

Now Playing: Young Michael Jackson on performing: 'I'm two different people, on and off-stage'

Now Playing: Girl Scouts on how Meghan Markle inspires them: 'She speaks up for women'

Now Playing: 'Lights, Camera, Summer: Inside the Blockbusters' Airs Tonight at 10/9c on ABC

Now Playing: 'Lights, Camera, Summer: Inside the Blockbusters' Airs Wednesday at 10/9c on ABC

Now Playing: 'Clueless' star Alicia Silverstone on trying 63 different outfits for the movie

Now Playing: Alicia Silverstone remembers 'Clueless' co-star Brittany Murphy's audition

Now Playing: Pilots who safely landed Southwest flight remember moment they knew there was trouble

Now Playing: Pilots who safely landed Southwest flight on their bond and their lessons for pilots

Now Playing: What pilots who safely landed deadly Southwest flight may have experienced in cockpit