NEW YORK — Trainer Jason Servis, whose horse Maximum Security was the 3-year-old champion in 2019, pleaded guilty Friday to federal charges involving a widespread scheme to drug horses.

The 65-year-old New Jersey-based trainer faces four years in prison when he is sentenced next May in U.S. District Court in Manhattan. He was the last defendant facing charges in the scheme, and now 23 of the 31 individuals charged have pleaded guilty.

Servis pleaded guilty in connection with his role in the distribution of adulterated and misbranded drugs intended for use on horses in his stable.

“Servis’ conduct represents corruption at the highest levels of the racehorse industry,” Damian Williams, U.S. Attorney for the Southern District of New York, said in a statement. “As a licensed racehorse trainer, Servis was bound to protect the horses under his care and to comply with racing rules designed to ensure the safety and well-being of horses and protect the integrity of the sport.”

Servis’ attorney, Rita Glavin, did not immediately respond to an emailed request for comment.

Servis was charged in 2020 after a wide-ranging investigation into doping in the horse racing industry. Racing authorities suspended his trainer’s license.

Maximum Security finished first in the 2019 Kentucky Derby but was disqualified for interference during the running of the race. The colt finished first in the $10 million Saudi Cup shortly before Servis’ arrest in March 2020. Saudi officials later withheld the winner’s share of the purse, citing Servis’ arrest and indictment.

“I don’t take any solace in other peoples misery, actually quite the opposite I feel some empathy for them,” Kentucky Derby-winning trainer Graham Motion tweeted, “but the reality is that those of us who were beaten by Jason Service’s (sic) horses have little to show for it other than losing money, owners and horses due to his success.”

Another New Jersey-based trainer, Jorge Navarro, is serving a five-year prison sentence after pleading guilty a year ago. Eleven of the defendants were trainers and seven were veterinarians.

Servis is the brother of trainer John Servis, who trained Smarty Jones to victories in the 2004 Kentucky Derby and Preakness before the colt lost his Triple Crown bid in the Belmont.