Re: A Question About Murder (A Novel Idea)?
Write the entire novel/book. THEN pick the title. It's no hurry really. Personally I think the word casualities is better used for wars and accidents. It denotes a loss more than anything else.
Here it sounds like you are dealing with revenge/vengeance and then kills/deaths/victims might be better options. But only you know the content so that's why you probably should set the title as well.