William Croll, a Thoroughbred trainer who was the son of Hall of Fame trainer Warren A. “Jimmy” Croll, committed suicide on Saturday in Hollywood, Fla., according to his son, Toby Croll. William Croll was 66.“It is extremely hard to understand, and we will probably never know why he left us so soon,” Toby Croll said.Although Croll maintained his own stable for most of his career, he assisted his father in preparing the champions Like a Charm, Parka, Forward Gal, Bet Twice, Housebuster, and 1994 Horse of the Year Holy Bull. Croll took over his father’s operation after the elder Croll retired in 2002. Jimmy Croll died in 2008.Croll grew up around horses and began working at the racetrack in the 1950s, walking hots prior to going to classes during high school, according to his son. Both William Croll and his father were based on the East Coast. In addition to his son, William Croll is survived by his mother, Roberta; a sister, Nancy; and his daughter Billie Rae. The family asked for donations to be made to the Virginia Horse Center Foundation in Lexington, Va,, in William Croll’s name.