Homicide detectives say someone found the body south of Sanger near Greenwood and Central.
Investigators went back to the scene Monday morning, hoping daylight would help unearth clues.
The area where the body was found is wide open, and the body is badly decomposed so detectives started out with little to go on.
"It only takes a small break and that gives us something that we can follow up and build upon. That just takes time and we have to be meticulous," Sgt. Leo Lopez of the Fresno County Sheriff's Department said.
The Sheriff's Office has not yet determined a cause of death and they're not sure if there was any foul play.
They're hoping to identify the man once the coroner performs an autopsy later today.