Authorities said Cooper was found Tuesday night in the shaft between the ceiling and the roof of the store after someone heard him screaming for help.
Emergency workers cut Cooper's sweatshirt away, poured vegetable oil taken from a store shelf down the shaft and handed him a rope. Four men on the roof then pulled him out, said Thorntown Deputy Marshal Chad Clendening. He was trapped for at least an hour.
"He's really lucky someone heard him yelling," Clendening said. "Otherwise, we probably would have been removing a corpse the next morning."
Earlier that day, Cooper had been on a team that cleaned the store's vent, authorities said. He reportedly told police he was able to move through the vent while he was working, so he figured he could use it to rob the store.
The Associated Press left a message Friday seeking comment from Cooper's attorney, Michael Gross.