Complex sentence: Early in the year he officiated Wilfred Benitez's fight against Roberto Duran for Benitez's super welterweight title and later he refereed Ray Mancini's first round knockout of Arturo Frias, a win that gave Mancini the WBA lightweight championship.
Split into simpler sentences: Early in the year he refereed Wilfred Benitez's fight against Roberto Duran for Benitez's super welterweight title. Later he was the referee in the Ray Mancini's first round knockout of Arturo Frias, a win that gave Mancini the WBA lightweight championship.