The man disappeared on July 28, when he was fishing with his friends on the Javai River, 200 km from the city of Palmas.
"We found slippers and a lighter near the river," Sergeant Ronaldo Barbosa told the Estadão newspaper.
According to him, locals are confident that the fisherman was eaten by alligators. They said they killed an animal that seemed suspiciously fat.
Eyewitnesses also claim to have found human remains inside the alligator, which are now being examined by a forensic medical institute in Palmas.