Serial killers began to gain the public's interest as early as the 1800s. Today, it is estimated that there are between twenty-five to fifty serial killers in America at any given time. The psychology of a serial killer is so very different from ours, which makes them so interesting. I have looked at the lives of the average serial killer and the characteristics they have in common. I have analyzed where they come from and even their DNA to determine what forms a serial killer. Then, I tell the story of the BTK Killer, Dennis Rader. Dennis Rader began killing women in 1974 and was arrested for his murders in 2005. I will analyze his life and determine the factors that I believe formed him into the serial killer he became.