The Oklahoma Highway Patrol has confirmed it found the body of a fisherman early Monday at Walnut Creek State Park, on the north side of Keystone Lake.
The man was last seen fishing by friends Saturday night.
They reportedly told the Lake Patrol troopers that when they left that evening, the man insisted on staying.
Troopers have not released his name pending the notification of family members; he was 49 years old.
When the went back Sunday to check on him, he was missing.
Foul play is not suspected at this time, but the Medical Examiner's office will determine if the man drowned or perhaps died of a medical condition and fell into the water.
He was fishing from the shore, and was not on a boat.