Hello. You did not say which Poe text this question refers to, which makes it impossible for it to be answered accurately and specifically, but I will try to help you in the best possible way.
In general, the monologues of Poe's characters point out that people who commit cruel crimes have a strong mental imbalance. These monologues always present awkward motives for the execution of these crimes and present delusional, unbalanced and uncontrolled characters.