Larry Jones, the trainer of this year's Kentucky Derby favorite, Friesan Fire, began serving a seven-day suspension on Sunday, six months after stewards issued the penalty for a clenbuterol positive last year at Delaware Park.\nJones will be suspended through May 9, according to John Wayne, the administrator of racing for the Delaware Thoroughbred Racing Commission. The suspension was issued last year after the Jones-trained Stones River tested positive for clenbuterol, a prohibited raceday medication that acts as a bronchial dilator, after a win in an allowance race on June 8 at Delaware Park.\nThe commission waited until this year to enforce the penalty because the Delaware Park meet was on the verge of ending when the final order for the suspension was issued, according to Wayne. Delaware Park's 2009 meet opened April 25.\n"In Delaware we believe that a suspension should be served when the live racing meet is being conducted," Wayne said. "It seems like the fair thing to do."\nThe clenbuterol positive was the first violation for Jones of a medication rule. Jones appealed the initial ruling, claiming that he had never administered clenbuterol to Stones River, but the commission upheld the ruling, citing the absolute insurer rule, which holds a trainer responsible for his horses regardless of the circumstances.\nJones has said he will retire at the end of this year. His Friesan Fire finished 18th in the Derby.