How does an author use narrative voice to create believable characters?

Tell the reader directly what the character is really like

Describe what the characters look like

Portray a character's thoughts and motivations

Use dialogue to let a character's words to show something important about his or her nature

Hope I helped -

Sleepy~

The answer is "passing blame".

Explanation:

The tones seen in this excerpt could be described as a fault, they indicate that perhaps the speaker also isn't responsible for the death.  On the other hand, he says also that guy's behavior was responsible for the "horrible monster" that Black Cat, because it had "seduced him" himself to also be murdered (or persuaded him). Thus the black cat is accused.