Serial killers are individuals who commit more than three murders in a time period of more than a month, on a trot, with some time gapping between these murders. The purpose of committing several murders back to back involves some desire for sex almost invariably. But FBI states that individuals often take to serial killing because of anger, gain, and thrill and quite often to seek attention. Some kind of personal gratification is involved behind serial killing. Ernst Gennat, a German police inspector had coined this term back in 1930. In the words of Pat Brown, “All serial killers want to win. They choose victims they can kill successfully”. Evidence can vary depending on the circumstances, the weather, and how long it has been hanging around. In reality, serial killers are of average intelligence. In reality, those rare few cases with good forensic evidence are the ones that make it to court. Often, a serial killer has no felony record.