forensics Flashcards
what is offender profiling
- tool employed by the police to narrow down the list of likely suspects.
- finds the probable characteristics of the offender
what if offender profiling based on
the idea that the characteristics of the offender can be deduced from the details of the offence and crime scene.
what does offender profiling include? (method)
- careful scrutiny of crime scene
- analysis of evidence
- witness reports
what are the two types of offender (according to the top down approach)
organised and disorganised
what are organised offenders
offenders that show evidence of having planned the crime in advance
- tend to have high iq, socially and sexually competent
- often married with children
how does an organised offender attack
- usually has preference for type of victim
- maintain high level of control
- operates with detached surgical precision
- little evidence left at crime scene
what is a disorganised offender
offenders that show little evidence of planning suggesting the offence may have been spontaneous
- tends to have low iq, unemployed, history of sexual dysfunction or failed relationships
- tend to live alone and live close to the offence
how does a disorganised offender attack
- body is left at scene
- little control from the offender
what is the top down approach
when evidence from the crime scene and other details of the crime are used to fit the offender into the categories of disorganised or organised
what is the evaluation for top down approach
- only applied to certain crimes. common offences (burglary) do not work bc crime scene reveals little about offender
- top down was made from interviews with 36 sexually motivated killers. CANTER argued it is not valid to rely on self report data
- organised or disorganised is overly simplistic. HOLMES suggests 4 types: visionary (god/devil is directing them), mission (eradicate people), hedonistic (thrill), power (complete control) serial killers
- unrepresentative,sample too small and only on serial killers
what is the bottom up approach
using statistics and a database to generate a picture of the offender and their likely characteristics
how does the bottom up approach work (method)
- systematic analysis of evidence left at the crime scene
- profile is data driven and profilers engages in rigorous scrutiny of the details of the offence
what is the aim of investigative psychology
to establish behaviours that are likely to occur at certain crime scenes.
creates statistical database which acts as a baseline for comparison
how does investigative psychology work (method)
- specific details of offence are matched against a database
- that reveals statistically probable details about the offender
- determines whether multiple offences are linked
what is interpersonal coherence
the way in which an offender behaves at the crime scene, including how they interact with the victim reflects their behaviour in everyday situations
how does interpersonal coherence help investigative psychology
- offender’s behaviour at crime scene may reflect their behaviour in everyday situations.
- the significance of time and place of the crime is also a key variable and may indicate where offender lives
what is forensic awareness
when individuals make an attempt to ‘cover their tracks’.
-indicates that they have been subject to police interrogation before/police have their dna or fingerprints on file
what is geographical profiling
the study of spatial behaviour in relation to crime and offenders
how does crime mapping work
- plot the areas of the crimes on a map
- draw a circle around all the crimes
- attacker should theoretically live in the centre of it
how does geographical profiling work?
- focuses on location of the crime as a clue to where offender lives
- relevant data includes crime scene, local statistics, local transport and geographical spread of similar crimes
what does geographical profiling assume
- offender will restrict criminal activity to an area they are familiar with
- earliest crimes are likely to be closer to the offenders base than later crimes
- as offender becomes confident they will travel further from comfort zone
what are the two models of offender behaviour (canter, larkin)
- MARAUDER (operates close to their home)
- COMMUTER (likely to have travelled a distance away from their home)
what are the strengths of the bottom up approach
+CANTER argues that bottom up profiling is more scientific than top down bc it is more grounded in evidence and psychological theory
+can be applied to a wide variety of offences, such as as burglary/murder/rape
what are the limitations of the bottom up approach
- 21 yo Rachel Nickell was stabbed 47 times and sexually assaulted in a frenzied attack on Wimbledon Common. In 2008, following examination of forensic evidence, Robert Napper was convicted of the murder. He had been ruled out early on in the initial investigation because he was several inches taller than the profile had claimed the offender would be.
- chemistry students produced a more accurate offender profile than experienced senior detectives. This implies that the bottom-up approach is little more than common sense and guess work.
what is the historical/atavistic approach to offending?
Lombroso suggested that criminals were genetic throwbacks, a primitive sub species who were biologically different from non criminals.
their savage and untamed nature meant that they would inevitably turn to crime
what does atavistic mean
reversion to something ancestral
how can criminal sub species be identified by (lombroso/atavistic form)
particular set of physical characteristics, mainly the face and head
what characteristics did the atavistic form include
narrow, sloping brow, a strong prominent jaw, high cheekbones and facial asymmetry.
dark skin and extra:toes, nipples or fingers
insensitivity to pain, use of criminal slang, tattoos and unemployment
what are the atavistic characteristics of murderers
bloodshot eyes, curly hair, long ears
what are the atavistic characteristics of sexual deviants
glinting eyes, swollen/fleshy lips and projecting ears
what are the atavistic characteristics of fraudsters
thin and ‘reedy’ lips
describe lombrosos study on atavistic characteristics
- examined facial and cranial features of italian convicts
- 383 dead criminals, 3839 living ones
- concluded her 40% of criminal acts could be accounted for by criminal subculture
what is the strength of atavistic form
+had important role in the shift away from theories based on feeble mindedness, wickedness and demonic possession
+was the forerunner to more biological explanations
what are the limitations of atavistic form
- racist undertones. majority of the features are found in people of african descent. his claims that the characteristics were uncivilised and primitive supporter the eugenic philosophy
- GORING compared 3000 criminals to 3000 non and concluded there were no particular cranial characteristics. he found that criminals are more likely to have below average IQ
- no control group
- characteristics can be affected by external factors such as poverty and poor diet
explain how criminal behaviour could be polygenic
no one single gene is responsible for offending.
what are candidate genes (in terms of criminal behaviour)
multiple genes that may be responsible for causing criminal behaviour
what does the MAOA gene do
controls dopamine and serotonin in the brain and has been linked to aggressive behaviour
what is the CDH13 gene linked to
substance abuse and attention deficit disorder
what does the diathesis stress model state
genetics influence criminal behaviour but this is moderated by the effects of the environment
how can a tendency towards criminal behaviour arise
through a combination of genetic predisposition and biological or psychological triggers, such as being raised in a dysfunctional environment.
what is anti social personality disorder
having reduced emotional responses and lack of empathy
what evidence supports that a brain area may explain criminal behaviour
several brain imaging studies demonstrated that individuals with anti social personalities have reduced activity in the pre frontal cortex
what did RAINE find
11% reduction in volume of grey matter in the pre frontal cortex of people with APD compared to a control group
what did KEYSERS find
only when criminals were asked to empathise did their empathy reaction (controlled by mirror neurons in the brain) activate
what does KEYSERS research suggest
that APD individuals are not totally without empathy but may have a neural switch that needs to be turned on in order to experience it
what are the limitations of genetic and neural explanations of criminal behaviour
- concordance rates in MZ twins are not high and leave room for non genetic environmental factors
- brain scanning studies show pathology in brains of criminal psychopaths, but cannot conclude whether these abnormalities are genetic or early signs of abuse
- term ‘offending behaviour’ is too vague
- it is biologically reductionist: twin studies never show 100% conc rats so genetics cannot be the only explanation for criminal behaviour
- biological determinist: presents us with dilemma for our legal system, if someone has criminal gene thst cannot be responsible for crime
what is the general personality theory
Eysenck proposed that behaviour could be represented along two dimensions: introversion/extroversion and neuroticism/stability.
the two dimensions combine to form a variety of personality traits
where do our personality traits come from (according to eysenck)
- biological in origin
- came about through the type of nervous system we inherit from our parents
- all personality types have an innate biological basis
what do extraverts have and what are their personalities like (eysenck)
- underactive nervous system
- constantly seeking excitement, and stimulation
- may engage in risk taking behaviour
- difficult to condition and do not learn from their mistakes
what do neurotic people have and what are their personalities like (eysenck)
- have an overactive nervous system
- tend to be nervous, jumpy and over anxious
- their general instability means their behaviour is often difficult to predict
what is the criminal personality type
neurotic extravert
what will a typical offender score highly on (eysenck)
psychoticism - cold, unemotional and prone to aggression