Walsmear's only reason for proving to himself that the fairies were real, was to assuage his conscience -- to convince himself that she died as a result of seeing fairies, as opposed to her committing suicide from guilt as a result of her having an affair with Walsmear. Castle's interest in the fairies, by this time, was purely self-serving; he fancied he had made an amazing discovery in the garden and prepared to take some photographs of the garden at night, using special lighting techniques. On his way to the garden the next night, however, Castle once again ran into Paolo and Shorty, whom Walsmear hired to steal the photographs from the Templeton house.
Paolo
Walsmear