Forensics - paper 3 Flashcards
Basis
offender profiling - top down approach
That characteristics of an offender can be deduced from the characteristics of the offence and the evidence at a crime scene, or from other sources
purpose
offender profiling - top down approach
To narrow the field of enquiry to a list of likely suspects
Holmes and Holmes (1989) - 3 main goals
offender profiling - top down approach
- Social and psychological assessment (personality, age, race, sex, employment, education, marital status)
- Psychological evaluation of belongings (possessions that could associate offender with crime scene E.G souvenirs/photos ect)
- Interviewing suggestions and strategies (once profile is complete the profiler is responsible for developing techniques for the offender once in custody - draw out information)
history of top down approach
offender profiling - top down approach
- Originated at the FBI behavioural science unit in the US (1970s)
- Carried out in-depth interviews with 36 sexually motivated serial killers E.G Ted Bundy, Charles Manson
- Developed a template which can be used to match evidence from a crime to classify a murder or rapist
what is the top down approach
offender profiling - top down approach
- The interviews - creation of two offender types
- Profilers start with pre-established typology and work down from this in order to assign offenders to a category based on witness accounts and evidence from the crime scene
- Organised offenders and disorganised offenders
how to do the top down approach
offender profiling - top down approach
- Stage 1 - data assimilation
- Gathering all evidence available including crime scene photos, post mortem results ect
- Stage 2 - crime classification
- Placing the crime into either the organised or disorganised category
- Stage 3 - crime reconstruction
- Done in order to develop prediction about the motives and behaviour of offender/victim
- Stage 4 - profile generation
- Based on all available information, identifying possible characteristics of the offender, including physical appearance and personality
Characteristics of crime scene - organised
offender profiling - top down approach
- Planned
- Vitum targeted
- Self control shown at scene
- Personalised victim
- Controlled conversation
- Aggressive acts performed before death
- Weapon absent from scene
- Body hidden from view at scene or removed
Characteristics of crime scene - disorganised
offender profiling - top down approach
- Unplanned
- Victim not targeted
- Depersonalisation of victim
- Conversation avoided
- Weapon often present
- Body left visible at scene
Classification of offender and likely characteristic - organised
offender profiling - top down approach
- High intelligence
- Socially competent
- Usually have a partner/spouse
- Skilled occupation
- Watches media coverage
Classification of offender and likely characteristic - disorganised
offender profiling - top down approach
- Low intelligence
- Socially awkward
- Unlikely to be in a relationship
- Poor employment history
- Little interest in crime on
third type of offender
offender profiling - top down approach
- Douglas eventually added a third offender type in 1992. This was known as the mixed and was added to classify those who don’t easily fit into the two original categories
- Incomplete theory - use att A03
Key study - canter et al (2004)
offender profiling - top down approach
- AIM
- to test the reliability of organised and disorganised offender types
- METHOD
- content analysis on 100 cases of serial killers in the US to see if features of typographies are distinctly different
- used the criteria set out by douglas et al (1992) to classify 3 crime in each series as organised or disorganised
- RESULTS
- Twice as many disorganised as organised crime scene behaviour was identified
- Only 2 behaviours co-occurred in organised typographies - body concealed (70%) and sexual activity (75%)
- Most other behaviours co-occur regularly in less than half of the crimes committed
- Further analysis failed to separate variables into distinctly organised and disorganised
- CONCLUSION
- No real distinction between organised and disorganised behaviour
- All crimes have an organised element
- It may be possible to distinguish between serial killers as a function of how they exhibit disorganised aspects of their activities, but probably better to look at individual personality
evaluation
offender profiling - top down approach
- Potentially very useful in allowing offences to be linked and facilitating predictions about the time-frame of the next attack and how the series of offences is likely to develop
- Analysis of offender profiles by snook et al (2007) found that they were based on scientific argument and evidence only minority of the time, judgements are subjective based on often incomplete or ambiguous evidence from a crime
- Assumes stable crime type (wilson et al 1997) - most offenders show both types and this shifts from crime to crime
- Based on a very small/unusual sample of males, applies to violent sexual crimes - tried to use for other crimes - female serial killers are very different (gender bias) - should only be used for sexually violent crime
back ground
offender profiling - bottom up approach
- Sometimes called the british approach
- Pioneered by David Canter who objected to the often ‘intuitive’ judgements made by profilers using the top down approach
- A data-driven approach that makes use of statistical data on similar crimes that have been committed, in order to make predictions about the characteristics of an offender
key ideas - .1. Interpersonal coherence
offender profiling - bottom up approach
There is a consistency between the way offenders interact with their victims and with others in their everyday lives
key ideas - .2. time and place
offender profiling - bottom up approach
- The time and location of an offenders crime will communicate something about their own place of residence/employment
- We will also look at this element in more detail when we look at geographical profiling
key ideas - .3. criminal career
offender profiling - bottom up approach
Crimes tend to be committed in similar fashion by offenders and can provide indication of how their criminal activity develops
key ideas - .4. forensic awareness
offender profiling - bottom up approach
Offenders who show an understanding of police investigation are likely to have had previous encounters with the criminal justice system
Geographical profiling
offender profiling - bottom up approach - Geographical profiling
- Based on principle 2 - time and place
- Canter and Young
- 4 key assumptions - locatedness, systematic crime location choice, centrality and comparative case analysis
.1. location
offender profiling - bottom up approach - Geographical profiling
There may be multiple locations involved in any given crime - all of these help to build a picture E.G may have killed and disposed of the body in different places
.2. Systematic crime location choice
offender profiling - bottom up approach - Geographical profiling
The assumption is that crime scenes are not random - the offender will likely have some kind of connection/familiarity with the location
.3. centrality
offender profiling - bottom up approach - Geographical profiling
- Crime scenes tend to cluster
- Have two types of offenders - commuters (who travel from home to commit their crimes) and marauders (stay local)
- Canter found that 87% of sexual offenders are marauders
.4. comparative case analysis
offender profiling - bottom up approach - Geographical profiling
Assumption that the crimes are being committed by the same person, increasing the precision of geographical profiling
Considerations
offender profiling - bottom up approach
- Assumes that the target of crime is distributed more or less evenly throughout the space
- Works well in cities as everything is all in one space
- Rural areas are more spread out
- Profiles and maps are easily corrupted/distorted by linking incidents incorrectly
- Could minimise by looking at correlation coefficient (0.8) (inter-rater reliability)