The term "Serial Killer" was first used by an FBI agent named Robert K. A serial killer is an individual who performs a mass homicide with an abnormal intent in mind. A serial killer is not an individual who kills multiple individuals with no rhyme or reason to it, this is known as a mass murderer. To a serial killer, there is much more in a killing. There are usually patterns, clues, or at least something that links a serial killer to his kills. Most serial killers can be classified as intelligent, if not highly intelligent. This is a common trait among serial killers, and it is one of among many other psychological traits that separates them from the common day to day murderer. In the beginning stages of a serial killer's life, there are many signs that can point out the psychological difference in the individual from the rest of society. These three significant childhood symptoms are known as the terrible triad. They consist of bed wetting after the age of 12, which occurs in 60% of serial killers. Fire-starting, which is an odd fascination that the child will have in burning objects, and animal torture. Most serial killers take a fascination in torturing animals as a child. An incredibly important fact is that most killers become isolated from their peer groups at around the ages of 8 and 12. This act severely deforms their psychological makeup. Not all these traits are true, they are only probabilities that are found the be common among the average serial killers. Some serial killers never wet the bed, and were quite popular and social as a child. The only common trait among every serial killer is that they have all been found to have been subjected to serious emotional or physical abuse during their childhoods.
To define a serial killer, the killer in question must meet a certain amount of requirements. There must be a minimum of 3 to 4 killings, with a period of no killing in between.