Lowen Dean Thomas was 37 when he disappeared from the Marshall State School in Marshall, Missouri. He was last seen on the morning of July 19, 1976, wearing a blue shirt and green trousers. Thomas had lived at the institution since 1947 and was described by family as shy and mentally disabled; they said he had never tried to run away before and were concerned he could not survive on his own outside the school.

Searches and police inquiries produced no immediate leads or confirmed sightings, and the case eventually was classified as an endangered missing person. The investigation has continued over the years but no significant developments have been reported and the family remains without answers.

If anyone knew Lowen, saw him around Marshall in July 1976, or has information about his movements from the Marshall State School, please come forward.