Witnesses said they saw a man in a camouflage jacket holding a gun on his chest and lying in the middle of the street on the spray painted "X," an unofficial memorial maintained by the publisher of a local conspiracy theory publication.
"I can honestly say I've seen it all," said Ron Rice, who works at the nearby Conspiracy Museum in downtown Dallas.
Rice said it initially appeared that the man had been struck by a vehicle. When police arrived, they found a man shot in the head and a small caliber revolver, Dallas Police Department spokesman Chris Gilliam said.
According to the Dallas County Medical Examiner's office, the man, who was not immediately identified, was in his 40s.
Kennedy was fatally shot as his motorcade drove through Dealey Plaza on Nov. 22, 1963.