An autopsy was completed Monday afternoon, and deputies hope it will help them make a positive ID.
A pair of fishermen made the discovery just after 5:00 p.m. in an area filled with trees and brush. Investigators say the body is that of a male who was badly decomposed.
Leo Lopez with Fresno County Sheriff's Office said, "It appears he'd been there a while, undetermined amount of time and it's safe to say he didn't die of natural causes."
Neighbors say the area is frequented by many people. The river draws locals out to fish and nearby cotton fields were harvested last week.
Some neighbors say they walk right by the location where the body was found. They were shocked to hear about the discovery in the dense brush.