In the movie Boy in the Striped Pyjamas (2008), the young protagonist Bruno befriends a Jewish prisoner, Shmuel, at a concentration camp near his home. At the end of the movie, Bruno sneaks away from home, breaks in to the camp in order to help Shmuel find his father, and subsequently is taken to a gas chamber to be executed, as he is mistaken for an actual prisoner.
His parents quickly discover he is missing, track him to the camp, and Bruno's father sees an empty barracks, indicating a gassing has taken place. However, they spend very little time searching the camp, and his mother breaks down in tears outside the fence without even seeing the empty barracks.
Why do they assume he has been killed so quickly, without a more extensive search of the area? Is this a case of the viewer knowing Bruno has been killed and they will find evidence eventually?