After having immersed myself in locked room mysteries I have come to the conclusion that most of the deceptions involve an accomplice – who usually ends up dead. In one entertaining story, The Triple Lock’d Room by Lillian de la Torre – the locked room had been searched prior to leaving the terrified victim alone to sleep and no one was found to be hiding. No one full size that is as the murderer turned out to be a dwarf type person masquerading as a child. Spaces a child could fit in where not searched and therefore the killer escaped detection. This picture, from a 1926 Chatterbox reminded me of the story, though it has nothing to do with it.
On the subject of locked rooms, I like what Michael Collins has to say in No One Likes to Be Played For a Sucker. “The locked room is an exercise in illusion – a magician’s trick. Otherwise it’s impossible, and the impossible can’t be done, period. Since it had been done, it must be a trick, a matter of distracting attention, and once you know what you’re really looking for, the answer is never hard.”