What would it take for you to kill someone? If you were murdered today, who is most likely to do it? We think of murderers as criminals or people with mental illnesses, but most murders each year are by people like us, and most victims are killed by someone they know. Is there a predictable cognitive progression and set of traits that can lead an otherwise law-abiding person to murder? Yes. Most books about murderers emphasize how they are different from us. In Psychology of Murder I will show how they are similar, how they rationalize what they have done, and the warning signs that if left unchecked can lead any of us to a tragic impulsive choice, killing friends, family members, even our own children. The decision to kill requires only a brief irrational moment in which you feel the other person deserves it. As you will see, even mass shooters and serial killers often start out on a very normal path but experience a gradual uninterrupted progression toward their evil acts.