Chapman was last seen outside of his family's mobile home on Alfred Gore Road in Alfred, Maine at 10:30 a.m. on June 2, 1971. He was playing in a sand pile approximately 25 yards in front of his residence and his mother was inside talking on the telephone. When she went out to check on her son, he was gone. Chapman has never been heard from again. An extensive community search lasting several days turned up no sign of him. The area around Chapman's home is rural, heavily wooded, brushy and swampy. An extensive search of the area, involving hundreds of volunteers, turned up no indication of the child's whereabouts. Authorities originally believed he wandered away and became lost; however, this possibility is now deemed unlikely since he was never located.

Police tracker dogs traced Chapman's scent through a field, past an apple orchard onto a farm, and down the driveway to the main road. The scent apparently stopped there; Chapman's father, who was an auxiliary police officer in 1971, believes he may have been placed in a vehicle at that location. Chapman's dog did not bark when the child disappeared, something his mother finds odd as the two were very close.

Chapman's case was reopened in 1993 at the request of his father. His parents are now divorced and his mother moved to New York after his disappearance. His case is unsolved.