What book is the monologue cold blooded murderer in?

You're likely thinking of the famous "I'm a cold-blooded murderer" monologue from the play "The American Crisis" by David Mamet.

The character delivering this monologue is "The Man," a cynical and violent character who is also a powerful and disturbing example of Mamet's writing style.

While it's not explicitly stated in the play, the monologue is often interpreted as a confession from a serial killer. It's a haunting reflection on the nature of violence and the detachment a murderer might feel.

The monologue is one of the most recognizable and powerful moments in Mamet's work and has been performed and quoted widely.