How did social workers, police officers, and federal agents interact with him for months without immediately acting on the obvious physical discrepancies?

The answer requires understanding something about how human cognition works under the specific conditions of grief and desperate hope.

When we want something to be true — when we need something to be true — we process incoming information very differently than we do under neutral conditions.

The desire to believe acts as a filter on perception, making the evidence that supports the desired conclusion more salient and the evidence that contradicts it less salient.

Carey Gibson flew to Spain knowing that her brother was supposedly there.