There are no suspects at this time, Louisville Police Lt. Barry Wilkerson said Monday, noting that police are investigating several altercations that occurred at the track.
Workers discovered the body around 5 a.m. and notified track security, who called police, said police spokesman Robert Biven.
Perez worked for veteran horse trainer Cecil Borel, who is the brother of three-time Derby winning jockey Calvin Borel.
"Those folks are devastated," said Churchill Downs spokesman John Asher.
Perez had been working for Borel since 2008, and had been found at Barn No. 8, which was not the one he normally worked at, Asher said.
About 400 people were located Saturday night in the rear of the racetrack, he said. "So we are trying to speak with as many people as we possibly can. We do have a few leads coming in."
Biven described the track's backside as "like a mini-city," with 48 barns, workers' dormitories and areas where trainers live. "It's a 24-hour operation," he said.
Perez was working at Churchill Downs along with his 19-year-old son, who identified his father's body.