Forensics

• Offender profiling

  A tool employed by the police when solving crimes where the crime scene can link to the offenders characteristics
• Top-down approach


  1. 1970s in America by the FBI's behavioural science unit

  2. Data for the top-down approach was gathered from interviews with 36 sexually motivated serial killers

  3. Profilers match what they know about the crime and the offender to these templates

  4. Murders and rapists are classified into either the organised or disorganised category
• Organised crime


  Crime scene detail would usually have little evidence and attempts to clean it up
• Disorganised crime


  Crime scene details may include sexual activity and leave the body on show
• FBI profiling process


  1. Data assimilation - the compiling of data from the crime scene, police reports and postmortems

  2. Crime classification - the profilers decide whether the crime scene is organised or disorganised

  3. Crime reconstruction - a hypothesis about the crime sequence, offender and victim behaviour

  4. Profile generation - a prediction of the offenders physical and behavioural characteristics
• A key study by canter et at in 2004 aimed to test the accuracy of organised and disorganised offender types. They found a significantly higher number of disorganised crimes and further analysis of the types of crime proved unable to distinguish between organised and disorganised crime.
• Bottom-up approach


  Aims to create a picture of the offender: age, characteristics, social background, ethnicity. Doesn't begin with fixed typologies, profile is date driven and builds as investigators scrutinise the offence.
• Investigative psychology


  • Uses statistical procedures and psychological theory to analyse a crime scene, establishes patterns of behaviour to create a database for comparison.
• Egger's 5 principles for bottom-up profiling

  • Interpersonal coherence - how a offender behaves at the crime scene or victim and the reflection on their everyday behaviour
  • Time and place - the location of an offenders crimes allow conclusion to their place of residence
  • Criminal characteristics - allow classification of the offender which can help narrow down the field or research
  • Criminal career - crimes tend to be committed in a similar fashion insight to how their activity will develop or where they will strike next
  • Forensic awareness - police interrogation awareness, mindful of covering their tracks
• Geographical profiling


  Emphasises the locatedness can reveal a lot about an offender because of the systematic crime and location choice
• Canter's circle theory


  Proposed 2 models of offender behaviour - marauder (operates close to home base) and commuter (travels further). Suggests a circular pattern known as a centre of gravity of offending behaviour which forms around the offenders usual residence.
• Atavistic form

  A biological explanation for offending behaviour developed by Lombroso in 1876. Suggested that criminals were biologically different to non-criminals, lacking evolutionary development and having 'atavistic' physical characteristics.
• Lombroso examined the skulls of 3839 living criminals and 383 dead using phrenology, concluding 40% of the crimes were accounted for by atavistic characteristics.
• Lombroso recognised that biological make-up was unlikely to be the sole cause of criminality, and proposed that an interaction with a person's environment also played a role.
• Genetic explanations


  Suggests that criminals inherit a gene or combination of genes that predispose them to commit crime.
• Candidate genes

  MAOA - controls dopamine and serotonin, low activity linked to impulsive and aggressive behaviour

  CDH13 - linked to substance abuse and ADHD
• Brunner syndrome - a rare genetic disorder caused by a MAOA mutation, resulting in lower levels of the MAOA enzyme and higher levels of neurotransmitters like dopamine and norepinephrine, leading to impulsive and aggressive behaviour.
• Neural explanations

  Suggest differences in brain function and structure between criminals and non-criminals.
• Raine et al 1997 found reduced activity in the prefrontal cortex and corpus callosum, as well as abnormal activity in the amygdala, in a group of violent offenders.
• Stimulation of the amygdala, which is part of the limbic system responsible for emotional regulation and aggression, can lead to aggressive behaviour.
• whose attorney argued that he had genetics that predisposed him to violent behaviour. Although he was eventually executed, a genetic explanation to offender behaviour could allow dangerous criminals to be excused from their crimes.
• Most of the research refers to the violent aggressive crimes such as murder or rape not applicable to all crimes.
• Biological explanations- neural explanations

  Neural explanations of offending behaviour suggest a difference in the brains between non criminals and criminals.
• Raine et al 1997


  • Found after studying 41 participants who where charged with murder or manslaughter and pleaded not guilty by reason of insanity that there was reduced activity for the offender group in the prefrontal cortex and corpus callosum after PET scans as well as abnormal activity in the amyglada.
• They concluded that violent offenders have abnormal brain function and reduced activity suggested the brains of offenders are slowed which may make them unable to react in an appropriate manner.
• Amygdala


  Part of the limbic system and is seen responsible for survival like emotional regulation and aggression, a stimulation of the amyglada could lead to aggressive behaviour.
• Protegal et al in 1996


  • Stimulating the amyglada of hamsters led to an increase of aggressive behaviour.
• Serotonin


  Linked to impulsiveness
• Moir and Jessel 1995


  • Found this link between serotonin and aggression.
• Dopamine


  Linked to reward
• Buitelaar 2003


  • Found that juvenile delinquents given dopamine antagonists which reduce levels of dopamine showed a decrease in aggressive behaviour.
• 8.5% of the US population have had a brain injury compared with 60% in US prisons
• Kandel and Freed 1989


  • Found that impaired functioning of the frontal lobe caused a tendency for individuals to exhibit emotional instability and inability to examine consequences.
• Mirror neurons


  Damage to MNS lack of empathy
• Weakness to the biological explanations to offender behaviour is that research could potentially have a negative effect in the legal realm. For example Charles Whitman murdered his wife and mother and killed 13 people in his university. It was discovered after he was shot that he had a tumour pressing on his amyglada which is responsible for emotional regulation. This could allow dangerous criminals to be excused from their crimes if neural dysfunctions like this case was found.
• Weakness to Eysenck Wilson and Daly 1985 argued that this is due to evolutionary factors and they suggest that women may have historically been attracted to risk takers for things like hunting. They looked at homicide cases and saw that in nearly all cases in the US the murderer was male and also single suggesting that from an evolutionary perspective they would be looking to boost their social status.
• Eysenck's theory of the criminal personality

  Behaviour could be represented along 2 dimensions Extroversion which is how much stimulation a person needs, and neuroticism which is how emotionally stable an individual is.
• Eysenck's personality theory


  • Consists of social, psychological and biological factors.
• Biological basis


  Eysenck suggests that our personality traits are biologically determined by the type of nervous system we inherit suggesting all personality types have an innate biological basis.
• Under active nervous systems

  Extroverts, constantly seek stimulation, likely to engage in risk-taking behaviours, don't condition easily