Indiana State Police received a call around 10 p.m., after ATV riders uncovered the scene.
Officials say the riders noticed that a white Ford truck had been parked near U.S. 150 and Pennington Road for more than a day, so they decided to look around the area.
That's when they found the decomposing bodies of a man and a woman under an old bridge.
Investigators believe the two victims were in a relationship prior to their deaths, and both appear to be middle age or older.
Because of the condition of the bodies police believe they've been deceased for several days.
"It was a help to us, it's going to be a help obviously to the family of these two individuals once we identify them. So they did a really good job. They did not touch anything at the scene, they merely observed the deceased and immediately called the Indiana State Police. So in the future if anyone would come across as a deceased person a body, do not touch anything, do not rummage through the scene. Immediately call the police, and that's what these fellas did," said Indiana State Police Sgt. Joe Watts.
An autopsy for both victims is scheduled for Monday.
"We do all of our evidence gathering at the scene, then we rely on the information from the autopsy to point us in the right direction. We usually have that... our detectives usually have an idea of what way they want to go with an investigation, but the autopsy will either point us in a different direction or confirm our suspicions, so that's what were waiting for," Watts added.
If you have any information about the case you're urged to call Indiana State Police at (765) 653-4114.