Definition: classification according to general type, especially in archeology, psychology or social sciences. Why use it: observe behaviour, see what type, identify and predict. Risk of typological thinking: oversimplification, chopping up continuum, inattention to situational factors, obvious vs actual clustering. Generalised from casual, informal interviews of opportunity with 36 incarcerated serial killers. Questions based on three categories: crime scene, victim trait, personal characteristics of offender. Using aspects of crime scene to describe suspect. Kill victim in one place and stage it elsewhere. Great lengths to make it difficult to discover. The stranger beside me by ann rule. Never thought hed be capable of it. He had a degree in criminal justice. Superior to other people, lonely by choice. Usually return to relive memories, not to see police discoveries. Blocks out memory of killing so literally does not remember the murder. Stored body parts of victims in apartment.