Forensics - Criminal Profiling Flashcards
Explain the process of Top-Down approach
Two main approaches to offender profiling
Top-Down
Bottom-Up
Explain the process of the Top-Down approach
Start with a template before analysing the crime.
Have pre-existing category, or typology, through which they see the crime scene.
(Organised and disorganised offenders).
Who introduced disorganised and organised
Roy Hazelwood - Classifying serial homicide crime scenes into organised and disorganised types.
Studied further by John Douglas and Robert Resler
Study by Douglas and Resler
Interviewed 36 convicted sexual murderers.
7 killed one person, 29 killed multiple victims
Concluded that behavioural and personality characteristics can be determined from evidence at a crime scene
Crime scene behaviours and personality traits of an organised offender
Behaviours:
Planned offence
Victim was a stranger
Controlled conversation
Restraints used
Body hidden
Weapon absent
Personality:
Average to high intelligence
Socially competent (talk and seduce victims)
Skilled work
Sexually competent
Living with partner
Crime scene behaviours and personality traits of a disorganised offender
Behaviour:
Spontaneous offence
Victim/location known
Minimal conversation
Minimal use of restraints
Body left in view
Weapon often present
Personality:
Below average intelligence
Socially inadequate
Unskilled work
Sexually incompetent
Living alone
David Canter study
Tested typology approach with data from 100serial killings in the USA
- Found no distinct pattern in the data for organised/disorganised murder
Criticisms of Top down approach
Sampling problems:
Relies on interviews done by FBI on 36 serial murderers - limited sample so harder to generalise.
Can only be applied to sexually motivated serial killers.
Data only based on American men - differs in women/other cultures
Based on self report from murderers who may want to exaggerate their crimes
Details of the Bottom-Up approach
Introduced by David Canter
Does not assume a fixed typology
Starts with details of the crime and works up to build an understanding of the offender from there.
Involves Investigative Psychology.
What is Investigative Psychology
Uses psychological theory and statistics to analyse rime scene evidence and generate a database of criminal behaviour patterns.
Data-driven approach (Investigative Psychology)
A statistical database that records details about crimes.
Identify patterns that occur across crime scenes - make predictions about the characteristics of an offender + help find relationships between crimes
Interpersonal coherence (Investigative Psychology)
The way the offender behaved at the crime scene will be consistent with how they behave in everyday life
Geographical profiling
The study of spatial behaviour in relation to crime + offenders - Crime mapping
Uses crime scene location and local knowledge to allow inferences to be made about the offender - where they live, work, socialise.
Circle theory:
Offenders tend to commit crimes within a spatial area that goes out from where they live
Types of geographical profiles
Marauders:
Have a home base location that they commit crimes out from
Commuter:
Have travelled a distance away from their home base
Schema Theory
Organised units of knowledge that we have developed through experiences
Help us to make sense of the world so that we can predict what is going to happen + how to respond appropriately.
John Duffy case
Committed 24 sexual attacks + 3 murders in North London
Analysed geographical information from crime scenes + analysed the data that the police had from all other similar crimes
Concluded the offender was a marauder, married with no children, had marriage problems, isolated, few friends, semi-skilled job, knowledge of railways + previous criminal record.
Able to make a match to John Duffy using these techniques
Comparison of Top-Down and Bottom-Up
Top-Down:
1. Based on the unreliable data of the murderers they interviewed.
2. Based on a limited sample of 36 serial sexual murderers - only applicable to sex related murderers + not other types of crimes
Bottom-Up:
1. Based on psychological theory (mental mapping + schemas) as well as statistical analysis of crime scene data - more objective and scientific
2. Based on investigative psychology and geographical profiling - not limited to one particular type of crime - more generalisable
Both:
Caution is needed with offender profiling as it is not always accurate and has the potential to mislead - danger in sticking too close to the profile created that other people can be missed - should be used as one tool among many
