You would think that speaking to a narcissist / psychopath about a murder they did would be hard. But it is not. Many psychologists have experienced this while interviewing known murderers.

The narcissist has to remain perfect. They can have no flaws. So, if something bad happens, that person dies, and a new person is formed. When speaking to the narcissist, the psychologist finds the criminal to speak quite openly about the murder, as if they are talking about something that someone else has done.