After Rodney King drowned in his backyard swimming pool in the quiet suburban city of Rialto, Calif., he was memorialized as a victim of police brutality. Every television viewer who saw the March 3, 1991, videotaped beating of King by LAPD officers has a visual memory of the incident — and memories, also, of Los Angeles burning a year later after the officers were acquitted by a jury in suburban Simi Valley. Few know what really happened.

In reporting King’s death at the age of 47, the New York Times called him a “symbol of the nation’s continuing racial tensions.” The …