What is the moral to the poem 'A case of murder'?

This is reminiscent of Poe's "A Telltale Heart". In that one the narrator kills an old man because he's repelled by his milky blue eye. Then he buries the man under the floor. But his conscience and the horror of what he's done cause him to hallucinate that he hears the old man's heart beating, and he eventually gives himself away. Here, the boy is repelled by the cat and kills it, but although he "gets away with it" and hides the body, the horror of his crime is stuck in his conscience and his guilt will eventually get the better of him and he'll have to confront what he did. I guess the message is that guilt will eventually out in a normal person.