Dr. Drew Pinsky on Rodney King's death: 'I feel angry because I know it didn't have to happen'

Rodney King was just a "misunderstood" sweet man who just couldn't shake his inner demons, Dr. Drew Pinsky, who treated him for alcohol abuse on his VH1 reality series, "Celebrity Rehab," said on his HLN news program on Monday night, one day after King was found unconscious at the bottom of his pool in Rialto, California. "I feel angry because I know it didn't have to happen," he continued. "After the anger passes, the sadness kicks in." Of King's three daughters, who appeared on "Celebrity Rehab" with their dad, Pinsky added, "I'm so devastated for them. They can't get their head around this."

Also on Dr. Drew's program were Bob Forrest and Jennifer Gimenez, who both work with him on "Celebrity Rehab." The two both painted King as a tender man, despite what his legacy was. "I just loved the guy," gushed Forrest. "He was just so gentle and sweet and kind."

[Read More: Rodney King legacy: 'Can we all get along?']

As for what killed King, Forrest was quick to predict it was likely because of his addictions. "It was alcoholism to me if you're swimming at 3 in the morning." Added Gimenez, who fought back tears as she spoke, "He really wanted [sobriety]."

In April, King appeared on Dr. Pinsky's show and revealed he was at peace in his life, after two decades of anguish. "I'm very happy and pleased to be alive through it all," he said. "I have some good people praying for me. You know I'm real comfortable with myself these days ... I don't drink like I used to …I've learned a lot over the years."

On "Celebrity Rehab" in 2008, King was very open about his struggles, which he attributed to the brutal beating he received at the hands of the LAPD in March 1991 after King, who had been drinking with friends, took them on a high-speed chase because he feared a DUI would violate his probation for a previous robbery conviction. Three of the four police officers who beat King, then just 25, were acquitted of their charges and a jury failed to reach a verdict for the fourth officer -- and thus touched off the L.A. riots in 1992, which resulted in 53 deaths and more than 2,000 injuries in six days until the United States Army National Guard got involved.

[Photos: L.A. Riots 20 Years Later]

In the years that passed, King turned to alcohol to numb the pain of what he went through. In 1993, he was arrested for DUI, and once again in 2003. In order to help King get past his issues from the incident, Dr. Drew brought him back to the same place the four officers had beat him in a very memorable and emotional "Celebrity Rehab" episode. In 2009, King appeared once again on "Celebrity Rehab" to mentor Dr. Drew's current patients. In the episode, he spoke proudly of being 11 months sober and seemed to really be on the right track.

[Read More: Major players from the 1992 Los Angeles riots]

King was found at the bottom of his swimming pool in Rialto, California, in the early hours of Sunday morning after his fiancée Cynthia Kelly -- who served as a juror in King's 1994 civil suit against the city of Los Angeles for his brutal 1991 beating at the hands of the police -- called 911. Kelly has reportedly told authorities that King was drinking and smoking marijuana in the hours before his death. Around 5 a.m., she awoke to her fiancé nude and beating on a window. Next thing she heard was a splash. Attempts to revive King were unsuccessful and he was pronounced dead an hour later.