Pending toxicology tests will help determine the cause of death, Deputy Jackson Harris said.
Almendarez's body was found about 20 yards from the tracks in some grass near East Tabor Avenue, Harris said.
Fairfield police Lt. Greg Hurlbut said Almendarez's father had reported him missing several weeks earlier. The body had been there for some time, Hurlbut said.
The area where he was found, which is behind houses, is not heavily traveled and there is no indication Almendarez was struck by a train, Hurlbut said.
Hurlbut said Almendarez, a Fairfield resident, was taking prescription drugs for mental health issues.