2004 summer, most of Korean were shocked from serial killer Ryo young chul\'s criminal behavior. He had kept anger to society and selected the victim randomly. He killed many females and senior persons. Korean National Police\'s investigation method to homicide depend on traditional homicide investigative methods. But serial killer\'s criminal behaviour is evolving frequently. Therefore traditional investigative method is no effective to serial homicide anymore. If traditional investigative method is old version virus vaccine, serial killer\'s criminal behaviour is newly appeared computer virus. Fortunately all of criminal has modus operandi independently. Any person comes into contact with an object or another persons, a cross-transfer of physical evidence happens. In the future it is impossible to escape from confrontation with serial killer. It can be prospect that more severe copycat serial killer will appear in Korean society. Based on the Ryo young chul\'s criminal behavior, I\'ll try to analyse the serial killer\'s modus operandi through various aspects.