Antonio Figueroa, 32, a stablehand who worked for trainer Raymond Einhorn, was fatally stabbed early Thursday in the Monmouth Park barn area.
Police responded to a 911 call around 2:30 a.m. and found the victim and "an excessive amount of blood," according to Monmouth County prosecutor John Kaye.
The police recovered a knife at the scene.
The New Jersey State Police and the Oceanport Police Department cordoned off a portion of the backstretch Thursday morning to conduct an investigation.