On an internationally acknowledged Scale of Evil, these are the world's worst serial killers. The qualifications for entry to this list of the vilest criminals of all time are a propensity for sadism, torture and murder without a shred of remorse. Using expert evidence, this book looks behind the shocking headlines and delves into the minds of monsters. What drove them to crime? What turned seemingly ordinary members of society into sick slayers. How did they self-justify their heinous deeds? And, quite simply, how did they get away with murder? Included in this catalogue of the world's most evil killers are men who committed crimes so monstrous that they almost defy belief yet to their neighbours and work colleagues seemed quite normal.