Frederick was last seen in Grahamsville, New York at 9:00 a.m. on May 25, 1955. His older siblings were at school and his mother was working in the garden when he disappeared. Frederick stopped in a cobbler's shed next to his home and spoke to his family's landlord. This is the last known sighting of him. He has never been heard from again and an extensive search of the area turned up no sign of him.

The police investigation initially focused on Frederick's parents and their landlord. Both parents passed polygraph tests and were cleared as suspects. When police searched the landlord's residence, they found numerous stolen items hidden in his garage and he was jailed. No one has ever been named as a suspect in Frederick's disappearance.

Frederick's mother always believed her son was kidnapped and sold. He had long hair at the time of his disappearance and his sister speculated someone could have passed him off as a girl to evade detection. Frederick's father committed suicide in 1968 and his mother died in 1979. Five of his seven siblings have also died in the years following his disappearance, but two of his sisters are still alive and hope he may be found. His case remains unsolved.