Depending on the jurisdiction you might end up paying quite a lot of money. Potentially lethal boobytraps left in derelict buildings are mostly illegal in the US[1] and in other western countries shooting a thief is generally illegal unless you can prove fear of bodily harm since you are escalating a situation from damage to property to damage to body. While the US is rife with stand your ground laws - most of the rest of the western world finds using potentially lethal force in response to property damage abhorrent.

1. https://www.youtube.com/watch?v=bV9ppvY8Nx4