Chapter Two: Definition of Serial Killer Serial killers are people who kill three or more victims in a period of more than thirty days with a cooling off period between each killing. Their murders usually have some of the same characteristics. People who kill for fun usually have some type of mental illness. Their crimes could perhaps have been prevented if their illnesses had been treated in time. The psychopath's illness is the least treated. Some murderers often plead not guilty by reason of insanity. However, it must be demonstrated that they did not know the difference between right and wrong. Even if a murderer is found not guilty due to mental deficiency, he cannot be freed. There are three categories of serial killers: organized killers, disorganized killers and medical killers. Organized assassins are the most difficult assassins to catch due to their intelligence and organization. Every detail of their murder is planned and they make sure not to leave any evidence behind. They often observe their victims for several days before tricking them into leaving with them. They take great pride in their “work” and pay close attention to media stories. Disorganized killers rarely plan the murders of their victims. They strike at random whenever the opportunity presents itself. They tend to move from city to city and take no precautions to hide their tracks. They usually have low IQ and are antisocial. Disorganized killers usually have no close friends or family. The Medical Killer is extremely rare but there have been cases where people have carried out their serial killings through medicine. One of these individuals was Harold Shipman, who I will discuss in more detail later in this thesis. They feel they have the pe... middle of paper... ...ortable that kills on their driving routes. There was a serial killer police officer named John Gerard Schaefer. He lived in Florida. While on his team he would kidnap teenage girls, tie them to trees, go back to work and after he was done, go back to rape and kill them. His alibi was always “I was at work when they disappeared” (Brown, 2003). Many serial killers suffer from antisocial personality disorder or dissociative personality disorder. They are also psychopathic, meaning they feel no empathy or guilt. They kill impulsively and make rules for themselves which are the only rules they follow. They have a "Mask of Sanity", which means they never allow anyone except their victims to see their true selves. They also resent society for their failures and can never take responsibility for their actions.