- Created by: RevisionBug01
- Created on: 02-04-19 10:29
Top down approach
An analysis of previous crimes creates a profile of a likely offender. Helps to predict and profile characteristics of potential offenders using the knowledge of the profiler to narrow the field of possible suspects.
- Work down in order to match what is known about the crime and potential offender to a pre existing template.
- Developed by the FBI in the 1970s. Hypothesised that all murders and rapists have similar characteristics.
Types of Offender:
Organised type of offender
Crime is planned, shows self control. Offenders are usually above average IQ, socially and sexually competent, usually lives with a partner and follows media coverage of their crime.
Disorganised type of offender
Little planning, random selection of the victim, crime scene is likely to contain evidence.
Stages in the top down approach
Six main stages (Douglas 2006):
1) Profiling inputs - Description of the crime scene, background information about the victim and details of the crime itself.
2) Decision process models - Data organised into meaningful patterns: murder type, time factors and location factors
3) Crime assessment - Whether the crime is classified as organised or disorganised
4) Criminal profile - Profile constructed of the offender including theories about their background, habits and beliefs
5) Crime assessment - Report given to the agency evaluating persons matching the profile are evaluated. No suspects is identified the process goes back to stage 2.
6) Apprehension - If a suspect is apprehended, the profile generating process is reviewed to check each stage.
Bottom up approach
A data driven approach where statistical techniques are used to produce predictions about likely characteristics of an offender, no assumptions are made about the offender prior to evidence colletion
Devised by Canter, three main features for investigative psychology:
People are consistent in their behaviour and therfore there will be links with elements of crime and how people behave in everyday life.
Certain behaviours may reveal an awareness of particular police techniques and past experience.
Small space analysis:
Data about many crime scenes and offender characteristics are correlated so that the most common connections can be identified.
Canter proposed that people reveal themselves through the locations they choose. The spatial relationships between different crime scenes and how they might relate to an offender's place of residence.
1. Circle Theory - Canter and Larkin proposed that offenders committ their crimes within a kind of imagined circle.
Marauder - The offender's home is within the geographical area in which crimes are committed
Commuter - The offender travels to another geographical area and commits crime within a defined space around which a circle can be drawn.
2. Criminal geographic targeting (CGT) Developed by Rossmo.
The formula produces a 3D map displaying data related to time, distance and movement to and from the crime scene. Map is called a jeopardy surface, colours indicate the likely closeness to the crime scene.