The First Deadly Sin by Lawrence Sanders

Wow this book is really interesting (1973). The author plays with philosophical issues in a very interesting way, combining them with intriguing characters. PW: A well-dressed man stalks the high-class neighborhoods of New York City. He is armed with an ice axe. His victims are strangers. And one cop, Captain Ed Delaney must solve a series of bizarre, gruesome murders that defy logic or method.