Lecture 4: Criminal Profiling and Geographic Profiling Flashcards
Barnum effect
occurs when an ambiguous personality description is perceived by the receiver of that description as a uniquely accurate portrayal of the self. In the profiling context, the Barnum effect has been examined as one possible explanation for why ambiguous profiles are viewed as accurate and useful by those who use profiling advice.
deductive (clinical) profiling
A form of profiling where the personality and behavioural features of an unknown offender are inferred from evidence relating to the crimes of that offender.
inductive (statistical) profiling
A form of profiling where the personality and behavioural features of an unknown offender are inferred from what is known about other offenders who have committed similar crimes.
offender profiling
A technique for identifying the major personality and behavioural features of an offender based upon an analysis of the crimes he or she has committed.
trait model of profiling
A model of profiling that is based on the classic trait model of personality. The basic idea is that the behaviours exhibited by offenders at their crimes (e.g., planning) reflects some underlying personality disposition within the offender (e.g., organization), which in turn can be used to predict how the offender will behave in other aspects of their non- criminal life (e.g., intelligent).
distance decay
Distance decay refers to the well-established finding that offenders are more likely to commit crimes closer to home.
geographic profiling
A form of profiling where an attempt is made to predict the most likely residential location of a serial offender based on where they have committed their crimes. Computerized geographic profiling systems are typically used to make these predictions.
criminal profiling
A technique for identifying the personality and behavioural features of an offender based on an analysis of the crimes he/she has committed
goals of profiling
- Suspect prioritization
- New lines of enquiry
- Interview strategies
- Predict dangerousness
- Flush out offender
the history of profiling
- Jack the Ripper (late 1800s): the police sergeant investigating the murder of many women created a profile of the unknown suspect, which was the first operational use of a profile in an investigation
- Adolph Hitler (mid-1900s): Langer created a profile of Hitler, which put profiling on the map
- The Mad Bomber (1950s): James Brussel, a forensic psychiatrist, created a profile of the Mad Bomber and the profile matched the perpetrator. Prof Bennell thinks that the perpetrator had seen the profile and dressed in a red tie to match it
the FBI profilers
- Robert Ressler, John Douglas, and Roy Hazelwood developed the FBI behavioural science unit
- This put profiling on the map as an investigative tool
profiling in Canada
- The RCMP Behavioural Sciences Section is responsible for profiling in Canada
- They employ criminal profiling, geographic profiling, truth verification (including polygraph), VICLAS: a computer system used to link serial crimes, and the National Sex Offender Registry
formula for a profile
WHAT + WHY = WHO
creation of VICLAS
Inspired by the investigative failures of the Clifford Olson and Paul Bernardo case
The FBI Model of Offender Profiling “The Organized-Disorganzed Model”
- An offender’s crimes can be classified as organized (well-planned) or disorganized (chaotic)
- Similarly, an offender’s background characteristics can be classified as organized (self-control, methodical) or disorganized (impulsive, disturbed, potential psychopathology)
- Crime scene behaviour said to reflect one’s background characteristics
organized behaviours
- planning
- use of restraints
- ante mortem
- use of vehicle
- control of victim
disorganized behaviours
- leave evidence
- position body
- post mortem
- keep body
- no vehicle
organized characteristics
- intelligent
- skilled in job
- decent car
- follows media
disorganized characteristics
- sexually ignorant
- knows victim
- lives alone
- lives close to crime
criticisms of profiling
- Theoretical underpinnings
- Prevalence of “mixed” crime scenes
- Ambiguous advice
- Myth of the expert
theoretical underpinnings
Many forms of profiling are based on the classic trait model, whereby we infer traits from behaviours and use these traits to predict other behaviours
problem with with the classic trait model
there is no empirical evidence to support this
prevalence of mixed crime scenes
- Crime scenes are rarely exclusively “organized” or “disorganized”
- Many crime scenes are considered mixed
- This leads to problems with classification
ambiguous advice
Many profiles are ambiguous
Alison et al., 2003 Barnum Effect study method
gave a class of undergraduates crime scene details, an offender profile, and suspect descriptions. Half of the students received genuine information and the other half received bogus information. Detectives then rated the accuracy of the profiles that the students created
Alison et al., 2003 Barnum Effect study findings
- Both groups rated the profile as fairly accurate and useful
- Provides evidence that ambiguous profiles can be interpreted to fit more than one suspect
myth of the expert
Profilers may be no better than bartenders at deriving characteristics from crime scene behaviour
Campbell’s myth of the expert studies
Campbell’s studies show that psychologists outperform professional profilers and professional profilers are only slightly better at constructing profiles than many other groups
issues with Campbell’s studies
- they aren’t using legitimate profiling tasks
- it is difficult to get profilers to participate in these studies
how do profilers respond to criticisms?
Some profilers downplay the need for empirical support by stating that the fact that their services are in such high demand proves their utility
Stuart Kind (1925-2003)
- Forensic scientist for the UK Home Office
- Called in as a consultant to the Yorkshire Ripper case
- Murders of girls and women occurring between 1975 and 1980
- He mapped where the crimes were being committed and calculated the centre of mass
- His prediction of the offender’s residence was very accurate
counterargument to profilers’ demand argument
you can’t equate demand with validity
does geographic profiling work?
Evidence shows that geographic profiling is useful
John Snow (1813-1858)
- Located the Broad Street pump as the location of the cholera outbreak in London by plotting the incidence of disease on a map
- Uses similar logic to geographic profiling
when was geographic profiling useful?
- Yorkshire Ripper Murders
- Green River Murders
where does a geographic profile fit in?
- Occurrence of a crime series
- Use of traditional investigative techniques
- Linkage analysis
- Criminal profile
- Geographic profile
- New investigative strategies
principles & assumptions behind geographic profiling
- Circle hypothesis
- Distance decay
limitations of geographic profiling
Geographic profiling works because serial offenders typically travel short distances to commit the majority of their crimes and live within the area of their criminal activity, but there are exceptions to this
goals of geographic profiling
- Suspect prioritization
- Patrol saturation and surveillance
- Neighbourhood canvasses
Marauder offenders
- Commit a crime and then come back to their home
- More likely for interpersonal crimes
Commuter offenders
- Travel to commit a crime
- More likely for property crimes
computerized geographical profiling systems
- Most police services use computer systems to conduct geographic profiling
- RIGEL and DRAGNET are the most commonly used
- They work by inverting the distance decay function
Snook, Canter, and Bennell, 2002 study method
- Had participants predict where the offender lives in either an untrained or trained condition
- Offenders in the trained condition were told about the circle hypothesis and the propensity of an offender to commit crimes close to home
- They then measured the accuracy of where the offender lived in relation
Snook, Canter, and Bennell, 2002 study findings
- Found that the trained condition improved significantly at time 2
- Dragnet was no better than the trained conditions at time 2
Snook, Canter, and Bennell, 2002 study conclusion
Concluded that if you don’t have the money, you can improve your ability to profile to the point where you do as well as Dragnet
circle hypothesis
Offenders tend to live within a circle defined by a diameter that is dictated by the two farthest crimes
