Seven-year-old Dennis Lloyd Martin vanished from Spence Field in the Great Smoky Mountains National Park during a family Father’s Day camping trip on June 14, 1969. Playing hide-and-seek with his older brother, Dennis wore a red t-shirt and green shorts and slipped out of sight behind a bush; when his father, William Martin, called for him minutes later the boy was gone.

A severe thunderstorm that evening washed away tracks and made the terrain dangerous. What followed was the park’s largest search to that date: about 1,400 rangers, military personnel and volunteers searched roughly 56 square miles, but no trace of Dennis was found. The search was called off in September 1969. A family later reported hearing a scream and seeing an unkempt man in the woods that day, though that lead was not pursued extensively at the time.

Does anyone who was in or around Spence Field on June 14, 1969, remember unusual activity, an unfamiliar person, or anything that might still help this case?