You didn't specify what story you were referring to, so I am going to take a leap here and assume that your question comes from the story "The Black Cat" where the narrator kills his wife.  In this story, the narrator talks about how he used to be a kind, loving person that doted on all types of animals.  However, he unfortunately succumbs to "The Fiend Intemperance," or to drinking too much, and his character changes.  He becomes irritable and violent, and often acts out against his pets, and he even verbally and physically abused his wife.

This continues for quite some time, during which the black cat haunts and torments him.  On the cellar stairs one day, he takes an axe to it, and his wife tries to stop him.  He then turns the axe on her, killing her.  He then proceeds to stick her into the basement wall, and seal it up using bricks and mortar.  The cellar walls worked well for this--one was easily broken down with a crow-bar, and then walled back up.  So, he hides his wife's body in the walls of the home itself, and that is where it is discovered later on in the tale.

If your question was about some other story that you were referring to, submit your question again, with more specific references.  I hope that helps to clear it up for you a bit; good luck!