Twenty-two years in the FBI, sixteen of them as a member of the Bureau's Behavioral Science Unit. Thousands of homicides, rapes, suicides, and other gruesome crimes. Roy Hazelwood, like many investigators, has seen it all. But unlike most, he's gone further -- into the dark and twisted psyches of serial killers and sadistic sexual offenders -- and has emerged as one of the world's foremost experts on the sexual criminal.

Now, acclaimed true-crime writer Stephen G. Michaud takes you into the heart of Hazelwood's work through dozens of startling cases, including those of the Lonely Heart Killer, the "Ken and Barbie" killings, the Atlanta Child Murders, and many more. Here Michaud and Hazelwood go beyond the lurid details, to a deeper understanding of the depraved minds behind the grisly crimes, in a stark, startling, and fascinating work you will not soon forget.