Los Angeles police say Cornelius' son was on the phone with him before the shooting. But when his son arrived at Cornelius' home, it was too late. He found his father with what detectives describe as a self-inflicted gunshot wound to the head.
Responding officers arrived at the home on the 12000 block of Mulholland Drive, owned by Cornelius, at about 4 a.m.
Cornelius was transported to Cedars-Sinai Medical Center, where he was pronounced dead shortly before 5 a.m., said Los Angeles County Assistant Chief Coroner Ed Winter.
"I know that he was having, like we all would at his age, some issues with mobility and driving. That's typical," said friend Gregory Alosio.
Some neighbors say they only saw Cornelius when he walked his dog and hadn't seen much of him in the past few years.
"I wasn't even sure if he still lived here because I haven't seen him for a couple of years," said neighbor Jim Botko. "I didn't know if he was sick or if he had some financial issues or whatever, but whenever I saw him, he was a very nice guy."
"He was an intense guy, but he had a big heart inside of him," said Alosio.
So far, a suicide note has not been found but police have ruled out any foul play in Cornelius' death.
Singer Smokey Robinson, who once performed on "Soul Train" with Aretha Franklin, talked Wednesday about his good friend.
"I had no idea that Don was emotionally in that place. I just saw Don recently and I knew that he was... I think he had some sort of an ailment or something like that, physically, but I had no idea that emotionally he was in that place," said Robinson.
"I am shocked and deeply saddened at the sudden passing of my friend, colleague, and business partner Don Cornelius," said Quincy Jones. "Don was a visionary pioneer and a giant in our business. Before MTV there was 'Soul Train,' that will be the great legacy of Don Cornelius. His contributions to television, music and our culture as a whole will never be matched. My heart goes out to Don's family and loved ones."
Music and film producer and former Motown Records chairman Clarence Avant said "Don Cornelius' legacy to music, especially black music, will be forever cemented in history. 'Soul Train' was the first and only television show to showcase and put a spotlight on black artists at a time when there were few African-Americans on television at all, and that was the great vision of Don. The music industry will forever."
"Soul Train" began in 1970 in Chicago on WCIU-TV as a local program and aired nationally from 1971 to 2006. Cornelius created, produced and hosted the show.
He was a trailblazer who changed the music industry for African-American performers. With his deep voice, he helped bring the best R&B, soul and later hip-hop acts to TV. The show introduced TV audiences to such legendary African-American artists as Aretha Franklin, Marvin Gaye and Barry White.
"It was a black 'American Bandstand' but the blackness of it all is what made it different," Cornelius said in a 2010 interview.
Over the decades, "Soul Train" traveled well beyond its initial audience, reaching out to everyone through music.
"He created something that is going to be everlasting and that had a great impact on society, much like Motown," said Robinson.
Cornelius stepped down as host in 1993, though "Soul Train" stayed on the air through 2006. He was inducted into the Broadcasting and Cable Hall of Fame in 1995 and received a star on the Hollywood Walk of Fame.
In 2009, Cornelius was sentenced to probation after pleading no contest to spousal battery. During his divorce that same year, Cornelius also mentioned health problems.