In the #1 "New York Times" bestseller "Mindhunter," John Douglas, who headed the FBI's elite Investigative Support Unit, told the story of his brilliant and terrifying career tracking down some of the most heinous criminals in history. Using behavioral profiling and criminal investigative analysis to get into the head and psyche of both the criminal and victim -- to feel what they felt at the critical moment -- Douglas helped crack many high profile cases, including the Trailside Killer, the Atlanta child murders, and the Tylenol murders. Now, working again with his co-author Mark Olshaker, Douglas delves further into the criminal mind with a series of chilling new cases in "Journey into Darkness" Follow the FBI's premier investigative profiler as he penetrates the minds and motives of the most terrifying serial killers. In "Journey into Darkness," Douglas profiles vicious serial killers, rapists, and child molesters. He is straightforward, blunt, often irreverent, and outspoken, but takes pains not to glorify any of these murderers. Some of the unique cases Douglas discusses include: The Clairemont killer -- Six women were found stabbed to death in San Diego, three in the same apartment complex. In each case, the killer entered through an unlocked door or window in the late morning to early afternoon. A suspect was in custody, tied to one of the murders through a DNA match. Douglas was called upon to use his profiling techniques to link the other five murders to the suspect. Douglas looked at the "signature" of the killer, and found that all the murders were committed by the same man. The prosecution used the profile to force the jury to find the defendant guilty of all six murders, if they felt he was guilty of the one murder. Celophus Prince was found guilty on all counts. The schoolgirl murders -- What became Canada's "trial of the century." Several schoolgirls disappeared in 1992; their bodies were dumped several weeks later, beaten and sexually attacked. Canadian police agencies contacted the FBI for help on the case and to get a profile on the killer and, according to witnesses, his accomplice. Following the advice of the Investigative Support Unit in Quantico, Canada aired a television special entitled "The Abduction of Kristin French," allowing agent Gregg McCrary to describe the killer's profile on air. Knowing that the murderer and his accomplice would be watching, he planned to confront the unknown killer, assuring him he would be caught.