The Illinois racing board is looking into a race that took place Tuesday at Fairmount Park.
The contest featured 70-year-old jockey Robert "Cowboy" Jones who was trying to set records as the oldest jockey to win a race and as the only jockey to win a race in seven decades.
Although Jones finished in second place, state horse racing regulators want to know if competing jockeys tried to conspire to let Jones win.
"The officials work for the State of Illinois so they are completely independent," Fairmount Park officials said in a written statement about the investigation. "They administer the races all over the state. The jockeys being questioned are independent contractors. They have nothing to do with Fairmount Park. It would be inappropriate for us to comment during an ongoing inquiry by state racing officials."