Forensics

• Top-down approach

  • Created by FBI in America
  • Using data from interviews with 36 sexually-motivated convicted murderers
  • categorised data as organised or disorganised - each had certain characteristics so can use in future to predict and catch offenders.
• Organised offender

  • evidence of planning
  • targets specific victim
  • high intelligence
  • socially and sexually competent
• Disorganised offender

  • Little evidence of planning
  • No pattern to victims
  • low Intelligence
  • socially and sexually incompetent
• Constructing an FBI profile

  1. data assimilation - review evidence from crime scene
  2. classify crime scene as organised or disorganised
  3. crime reconstruction - hypotheses for sequence of events
  4. profile generation - hypotheses relating to likely offender
• Strength of top-down approach

  The approach can be applied to other crimes such as burglary. For example, this has led to an 85% increase in solved cases of burglary in some US states. This adds new categories such as interpersonal and opportunistic, suggesting there is wider application than assumed.
• Limitation of top-down approach

  The evidence it is based on. Of the 36 murderers interviewed only 12 were disorganised - this is a poor sample as it was not large or randomly selected and the interviews were not standardised so cannot be compared. Therefore, the approach doesn’t have a sound scientific basis.
• Limitation of top-down approach

  Organised and disorganised types are not mutually exclusive, so it can be difficult to classify offenders as one or the other. They may have contrasting characteristics such as high intelligence but commits a spontaneous crime, suggesting that this typography is more of a continuum.
• Bottom-up approach

  • uses systematic analysis of crime scene evidence to generate hypotheses of offender characteristics
  • Interpersonal coherence - the way an offender behaves at the scene and interacts with their victim may reflect everyday behaviour
  • significance of time and place - offender may live close to crime scene
  • forensic awareness - focuses on those who may have been interrogated by police before.
• Investigative psychology 


  Aims to establish patterns of behaviour likely to occur across crime scenes to develop a statistical database acting as a baseline for comparison so specific details can be matched to reveal details and help determine whether crimes are linked.
• Geographical profiling


  Uses information about the locations of linked crimes to make inferences about the operational base of an offender, based on the principle of spatial consistency. This can be used to create hypotheses about the offender’s modus operandi.
• Limitation of bottom-up approach

  Not as scientific as it claims to be. This approach uses objective statistical techniques and computer analysis, making them scientific. However, these techniques are only as good as the data they are based on - data only relates to caught offenders, telling us nothing about patterns of unsolved crimes.
• Strength of bottom-up approach

  Evidence suggests it is useful. For example, the case study of the Railway Rapist, who attacked 26 women all near railway stations in London. Police constructed a profile that enabled them to catch the offender, who fitted the characteristics. However, case linkage depends on the database used so it may be difficult to solve crimes which have few links between them, so the approach isn’t entirely useful.
• Limitation of bottom-up approach


  Geographical profiling may not be sufficient on its own, as it relies on the quality of data provided. Recording of crimes is not always accurate and many crimes are not even reported, questioning the usefulness of an approach relying on geographical data. Other factors may be just as important (such as timing of the offence), so geographical profiling alone may not alway lead to capture of an offender.
• Atavistic form


  Physical features due to evolution - primitive form so less sophisticate - that lead to offending behaviour, used to identify criminals.
• Lombroso’s theory 


  Initially performed an autopsy of an Italian criminal and found an indentation on the back of his skull, which led him to believe that criminals could be identified by physical defects, so wanted to investigate whether there is a genetic cause of criminality. Studied 380 dead criminals and found 40% showed atavistic form.
• Strength of biological historical expl

  Lombroso is seen as the father of modern criminology. He emphasised scientific investigation of criminals rather than moralistic discourse (judged as weak), and led offender profiling. Therefore, the theory was useful and scientific for its time.
• Weakness of biological historical expl

  Lombroso’s work has been criticised for its racist undertones. For example, many atavistic features such as dark skin and curly hair are more likely to be found in those of African descent. So he suggested that some ethnicities were more likely to offend, fitting eugenic views of the time. Therefore, aspects are subjective and influenced by racial prejudices, having negative implication.
• Limitation of biological historical expl

  There is contradictory evidence. For example, a study compared 3000 offenders and non-offenders and found no evidence of facial and cranial differences but found lower IQ. This undermines Lombroso’s theory.
• Limitation of biological historical expl

  Lombroso’s methods were poorly controlled. For example, he didn’t use a control group, resulting in confounding variables such as poverty and education which may link to offending behaviour. Therefore, his research cannot be regarded as scientific, lacking internal validity.
• Pre-frontal cortex in relation to offending

  Responsible for controlling behaviour, often Low arousal in criminals - inherited or result of environmental factors.
• Raine (2000)


  Studied those with antisocial personality disorder (APD) and found they have reduced activity in pre-frontal cortex and 11% less grey matter. This suggests their is a neural deficit in people with APD, which may cause behaviours such as lack of fear and Low arousal.
• Role of mirror neurons

  Research suggests offenders with APD can experience empathy but only when asked to, as mirror neurons not always active. This allows them to commit crimes with less guilt.
• Christiansen (1977)


  Studied 3500 pairs of twins in Denmark and found concordance rates of 35% for MZ twins and only 13% for DZ twins.
• Crowe (1972)


  Found that adopted children whose biological mother had a criminal record had a 50% risk of also having a criminal record (control group 5%).
• Bruner (1993)


  Studied a dutch family and found the males had a genetic condition resulting in Low IQ and deficiency in MAOA - leading to over-excitation of nerves in stressful situations (aggression).
• Limitation of genetic expl

  Assumes twins share equal environments. However, this may apply to MZ twins more than DZ twins as they look identical so are often treated the same. So higher concordance rates for MZ twins may just be because they are treated more similarly.
• Strength of neural explanation

  There is support for the link between crime and the frontal lobe. For example, one study found that those with frontal lobe damage were impulsive, emotionally unstable and didn’t learn from their mistakes. This supports the theory that brain damage may cause offending behaviour.
• Limitation of genetic and neural expl

  It is biologically deterministic. The approach suggests that offending behaviour is due to biological factors which are uncontrollable, suggesting an offender should not be held responsible for a crime. This complicates the principle that we take responsibility for our actions, having negative implications.
• Strength of genetic expl

  There is support for the diathesis-stress model of offending. For example, a study on rhesus monkeys found that this with a genetic predisposition for aggression were not agressive if they received supportive mothering. This shows that genetics play an important role in offending but an environmental trigger is needed.
• Eysenck’s personality inventory (EPI)

  A psychological test used to measure extroversion, neuroticism and psychoticism to determine personality.
• Extroversion


  Chronically under-aroused nervous system, leading to sensation-seeking and risk-taking behaviour to increase cortical arousal.
• Neuroticism


  Unstable, unpredictable behaviour - moody and insecure. This is the result of an instability in the sympathetic nervous system.
• Psychoticism


  Cold, heartless and with an inability to feel remorse. This is related to increased testosterone levels, so more apparent in males.
• Limitation of eysenck’s theory

  Doesn’t take into account cultural factors. For example, a study on Hispanic and African-American offenders found all groups (based on crime committed) showed lower extroversion than control group. Therefore, the theory is culturally relative so cannot be generalised cross-culturally.
• Strength of eysenck’s theory

  There is supporting evidence. For example, Eysenck & Eysenck compared 2000 prisoners EPI scores with a control and found they had higher scores on all dimensions. However, Farrington did a meta-analysis and found offenders scored High on psychoticism but not the other dimensions. This challenges the theory.
• Limitation of eysenck’s theory

  The EPI is not a reliable or valid way of measuring personality. For example, personality cannot be reduced to a score, as it is complex. It is also fluid, changing over time as our experiences shape us. Our perception of our personality may also change in response to mood, so the EPI may not measure what it intends to. However, it is still useful at allowing us to distinguish between criminal personalities and normal traits.
• Moral reasoning theory

  • Suggested by Kohlberg
  • evidence based on peoples responses to moral dilemmas.
  • found offenders= pre-conventional stage
  • non-offenders= conventional and beyond
  • pre-conventional characterised by a need to avoid punishment and gain rewards, associated with childlike reasoning.
• Cognitive distortions 


  Faulty, biased and irrational ways of thinking that mean we perceive ourselves, others and the world inaccurately and often negatively.
• Hostile attribution bias


  A tendency to judge ambiguous situations as Confrontational when they are not, triggering a disproportionate, violent response.
• Minimisation


  A type of deception involving downplaying the significance of an event, when dealing with feelings of guilt.