© UnknownRodney King was beaten while in police custody in 1991
His fiancee found his body at the bottom of a swimming pool, but there was no sign of foul play.
King was a victim of police brutality in 1991, but the officers involved were acquitted the following year.
The verdict triggered clashes between black youths and police which left more than 50 dead and thousands injured.
The beating was filmed by a bystander and part of the film was shown by media outlets across the world, causing public outrage.
A later trial resulted in two of the four officers being jailed.
King suffered brain damage during the beating. He sued the City of Los Angeles and won $3.8m (£2.5m) compensation.
Rialto Police Captain Randy Deanda said on Sunday King was found "unresponsive" at the bottom of his pool and was pronounced dead at 06:11 (13:11 GMT).
Thought he was doing well out of rehab, alcohol wasn't it? He was on one of those reality tv shows a while back. Not much data in this report.