Forensics Flashcards
What is offender profiling?
A scientific tool of identifying who committed the crime. Aims to narrow the list of suspects down by looking at the characteristics of the offender and environment to build the profile.
The Top Down Approach
Originated in USA in 1970s
Created from in depth interviews of 36 sexually motivated murders including Ted Bundy.
Data categorised into organised and disorganised crimes. These had certain social and psychological characteristics which they used in future situations. They would match data of the crime scene with characteristics of categories. Then they would predict other likely characteristics, used to find offender.
Organised types of offenders
Evidence of planning crime in advance
Certain type of victims targeted
Little evidence left
Offender has high level of control during crime
Tend to have a family-married
Tend to have above average IQ, a profession
Socially and sexually competent
Disorganised types of offenders
Little evidence of planning
Crime reflects impulsive nature of attack
Little control of crime, lots of evidence left
Lower IQ and failed relationships
Live alone and close to crime scene
What are the 4 main stages of constructing an FBI profile?
- Data assimilation
- Crime scene classification
- Crime reconstruction
- Profile generation
What is data assimilation?
Where the profiler reviews evidence eg photographs
What is crime scene classification?
organised/disorganised
What is crime reconstruction?
Hypotheses in terms of sequence of events, behaviour of victim.
What is profile generation?
Hypotheses related to likely offender
Demographic background, behaviour
Evaluation of top down approach to offender profiling?
There is evidence to support of the organised offender. Canter et al. looked at 100 US serial killings using ‘smallest space analysis”. Wanted to assess the co-occurrence of 39 aspects of serial killings. Whether there was torture, etc. The analysis revealed a subset of behaviours of many serial killings which match the FBI’s typology for organised offenders. Shows validity in organised offenders.
Limitation is the evidence it is based on. In the 36 in-depth interviews, the FBI agents did not select a large or random sample. No standard set of questions so interviews not standardised or comparable. No scientific research to support.
Organised and disorganised are not equally exclusive as offenders have multiple characteristics and usually do not fit into one type. They are likely to be a continuum.
What is smallest space analysis?
A statistical technique that identifies correlations across diff samples of behaviour.
Where did the Bottom Up Approach originate and what does it involve?
In the UK and it involves investigative psychology and geographical profiling.
Investigative psychology
-Statistical analysis involves using statistical procedures along with psychological theory, to analyse crime scene evidence. Aims to establish patterns of behaviour that are likely to coexist or occur across the crime scene which develops a statistical database which acts as a baseline comparison so specific details of offences can be matched against the database to reveal important information about the offender. Determines whether series of offences are linked.
-Interpersonal coherence is the way the offender behaves at a scene, which may reflect their everyday behaviour.
-Significance of time and place may indicate where offender lives
-Forensic awareness describes those individuals who have been in subject of police investigation before, their behaviour represents how mindful they are of covering their tracks.
