Heavyweight boxer Ken Norton Sr. passes away at 70 - The heavyweight who defeated Muhammad Ali began boxing at Camp Pendleton

SAN DIEGO - Heavyweight boxer Ken Norton Sr., who stunned the sports world 40 years ago by defeating Muhammad Ali at the San Diego Sports Arena, died today at the age of 70.

Norton, who broke Ali's jaw and won a split decision in the San Diego fight, was defeated by Ali in rematches at the Forum in Inglewood later in 1973 and Yankee Stadium in 1976.

Family and friends said Norton, who died in a hospice facility in Las Vegas, had been in poor health for several years following a series of strokes, according to reports.

Norton began boxing at Camp Pendleton in northern San Diego County and turned professional in 1967.

He compiled a 27-1 record before the first fight with Ali, which took place on March 31, 1973. He broke Ali's jaw in the second round, but Ali refused his trainer's pleas to come out of the fight. The bout continued, and Norton was afterward declared the winner.

Norton was awarded the World Boxing Council heavyweight title in 1978 when then-champion Leon Spinks declined to fight its No. 1 contender, Larry Holmes, opting instead for a rematch with Ali, who he had defeated earlier that year to win the title.

Holmes took the title from Norton on a 15-round split decision.

Norton retired in 1981 with a 42-7-1 record. His survivors include a son, Ken Norton Jr., who was a standout linebacker at UCLA and in the NFL.