PORTLAND, Ore. -- Tom and Betty West committed their mentally disabled son to a state institution. His name was Richard, and he was three years old. It was 1959. The massive complex was remote and family ties not encouraged. The state eventually moved Richard to a different facility without informing the Wests of the location. Four decades passed without a family member laying eyes on Richard.

As they entered their 80s, the Wests thought increasingly about Richard, the fifth of their eight children. How was he? Where did he...