Forensics Flashcards
Problems in defining crime
Crimes are acts against the law.
Definitions of crime differ across cultures and change over time.
Ways of measuring crime: Official Statistics
Government records of total number of crimes reported to the police and recorded in the official figures.
Published on an annual basis and provide a ‘snapshot’ of the number of crimes occurring in the country.
Allows government to develop crime-prevention strategies and policing initiatives.
Ways of measuring crime: Victim Surveys
Record people’s experiences of crime over a specific period.
The crime survey for England and Wales asks people to document crimes they have been a victim of in the past year. Separate survey for younger people.
Ways of measuring crime: Offender Surveys
Individuals volunteer details of the number and types of crimes they have committed. Tend to target groups of likely offenders based on ‘risk factors’, such as previous convictions. Looks at indicators of repeat offending.
Evaluation of defining and measuring crime
✗ Official Statistics may underestimate crime: many crimes go unreported to police that only around 25% of offences are included in the official statistics. The other 75% = ‘dark figure of crime’.
Farrington and Dowds found Nottinghamshire police were far more likely to record thefts under £10 than other countries.
✓✗ Victim Surveys have a greater degree of accuracy: surveys include crimes not reported to police. But they rely on accurate recall - may distort crime figures.
✓✗ Offender surveys provide insight: gather information on how many people are responsible for certain offences. But offenders responses may be unreliable - they conceal serious crime/ exaggerate.
- ‘Middle class’ crimes are under-represented (fraud)
Top-Down Approach: Offender Profiling
Match crime/ offender to pre-existing templates.
- Organised: evidence of planning the crime, victim deliberately targeted, high degree of control, little evidence left behind, above average IQ, skilled professional job.
- Disorganised: little evidence of planning, crime scene reflects impulsive nature of act, below average IQ, history of failed relationships.
FBI Profile Construction: Top-Down Approach
1) Data assimilation: review of evidence (photographs etc.)
2) Crime scene classification: organised or disorganised.
3) Crime reconstruction: generation of hypotheses about the behaviour and events.
4) Profile generation: generation of hypotheses about the offender.
Evaluation of the Top-Down Approach
✗ Only applies to particular crimes: common offences (e.g. burglary, destruction of property) do not lend themselves to profiling because the crime reveals little about the offender. Limited approach to identifying a criminal.
✗ Based on outdated models of personality: the typology classification system is based on the assumption that offenders’ patterns of behaviour are consistent across all situations and contexts.
- Alison et al. argue this is outdated as it sees behaviour as drive by dispositional traits rather than by constantly changing external factors. Poor validity of approach.
✗ Little support for ‘disorganised offender’: Canter et al. used smallest space analysis of 100 murders in US, each case was examined against 39 characteristics typical of organised and disorganised killers. Findings didn’t show a disorganised type.
Bottom-Up Approach: Offender Profiling
Investigative psychology
Profile is ‘data-driven’ and emerges as the investigator rigorously scrutinises the details of a particular offence.
Aim is to generate a picture of offender’s characteristics and background through analysis of evidence.
Bottom-Up Approach - Statistical analysis
Investigative psychology
Detects patterns of behaviour that are likely to occur across crime scenes. Develops a statistical database which acts as a baseline for comparison.
Bottom-Up Approach: Interpersonal coherence
Investigative psychology
The way an offender behaves at the scene may reflect everyday behaviour (e.g. controlling).
Their behaviour has coherence.
Bottom-Up Approach
Geographical Profiling
Inferences about the offender based on location-crime mapping. Can also be used alongside psychological theory to create hypotheses about the offender and their modus operandi.
Canter and Larkin:
Maurader - operates close to home base.
Commuter - likely to have travelled a distance away from usual residence.
Circle theory: pattern of offending locations is likely to form a circle around offender’s usual residence. Offender’s spatial decision-making provides insight into nature of offence (planned or opportunistic. etc)
Strengths of bottom-up approach
✓ Support investigative psychology: Canter and Heritage - content analysis of 66 sexual assault cases using smallest space analysis. Several characteristics were commonly identified in most cases (e.g. use of impersonal language). Can lead to an understanding of how behaviour may change = useful.
✓ Supports geographical profiling: Lundrigan and Canter - collated information from 120 murder cases involving serial killers in the US. Smallest space analysis revealed spatial consistency in behaviour of killers. = Key factor.
✓ Scientific basis: more objective than top-down - more psychological evidence, less speculation, use in judical process.
✓ Wider application to a range of offences. Techniques such as smallest space analysis can be used in investigation of crimes. More valuable as an investigative technique.
Biological Explanations: Atavistic Form
- Lombroso
Proposed criminals were ‘genetic throwbacks’ - a primitive sub-species who were biologically different from non-criminals. Laid foundations for modern offender profiling.
Offenders lack evolutionary development - ‘savage and untamed nature’ = impossible to adjust to civilised society and would inevitably turn to crime.
Lombroso saw criminal behaviour as an innate tendency.
Atavistic features
= Biologically determined. Mainly features of the head and face:
- Narrow sloping brow.
- Strong prominent jaw.
- High cheekbones.
- Dark skin.
- Facial asymmetry.
- Use of criminal slang.
- Unemployment.
- Tattoos.
Atavistic Form: Psychological ‘markers’
Linked to particular types of crime.
E.G. Murderers = bloodshot eyes, curly hair, long ears.
E.G. Sexual deviants = glinting eyes, swollen, fleshy lips.
Lombroso found 40% of criminal acts associated and accounted for by atavistic characteristics.
Strengths of Atavistic Form
✓ Large contribution to criminology: Lombroso = ‘the father of modern criminology.’ Shifted emphasis from moralistic discourse to scientific discourse. His theory heralded the beginning of criminal profiling.
Limitations of Atavistic Form
✗ Racial undertones: e.g. curly hair and dark skin, most likely to be found among people of African descent - uncomfortable and controversial legacy overshadows his work.
✗ Goring’s research: compared 3000 criminals to 3000 non-criminals. No evidence that offenders are a distinct group with unusual physical characteristics.
✗ Poor control in research: didn’t compare with non-criminal control group - significant differences in atavistic form may have disappeared if he had.
✗ Many of the criminals he studied had history of psychological disorders which may have acted as confounding variables.
Biological explanations: Genetic Explanations
Lange studied 13 MZ and 17 DZ twins, where one twin spent time in prison. 10 of the MZ twins had a co-twin who was also in prison.
Crowe found that adopted children who had a biological parent with criminal record had a 50% greater risk of criminal record by age 18. Adopted children whose mother didn’t have a criminal record only had 5% risk.
Genetic Explanations: Candidate Genes
Tiihonen et al. did a genetic analysis of 900 offenders and revealed 2 genes associated with violent crime:
- MAOA gene controls serotonin and dopamine - linked to aggression.
- CDH13 linked to substance abuse and attention deficit disorder.
High risk combo lead to individuals being 13x more likely to have violent disorder.
Genetic Explanations: Diathesis-Stress Model
Tendency of criminal behaviour may come about through a combination of:
- Genetic predisposition (diathesis).
- A biological or psychological stressor or ‘trigger’ (e.g. criminal role models or dysfunctional upbringing).
Strengths of Genetic Explanations
✓ Support for diathesis-stress model: Mednick et al. studied 13,000 Danish adoptees and criminality (having one conviction at least). When neither biological or adoptive parents had convictions, the percentages of adoptees that had a conviction was 13.5%. Rose to 20% when either of biological parents did, and 24.5% when both adoptive and biological parents did.
- Both genetics and environment influence criminality.
Weaknesses of Genetic Explanations
✗ Methodological problems with twin studies - Lange’s research was poorly controlled (based on appearance not DNA testing for judgements on if twins were MZ or DZ).
✗ Most twins are reared in the same environment - concordance rates may be due to shared learning experiences rather than genetics. Confounding variables mean twin studies may lack validity.
✗ Methodological problems with adoption studies - lots of adoptees maintain contact with their biological parents. Difficult to assess the environmental impact the biological parents might have had.
Biological Explanations: Neural Explanations
Antisocial personality disorder: there may be neural differences in the brains of criminals and non-criminals.
APD - associated with a lack of empathy and is suffered by many convicted criminals.
Less activity in prefrontal cortex = less emotional regulation: Raine et al. found 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls.
Mirror neurons: Keysers et al. found that only when criminals were asked to empathise did they show an empathy reaction (controlled by mirror neurons).
- APD individuals do experience empathy, but may have a ‘neural switch’ that turns on and off.
- In a normally functioning brain the empathy switch is permanently on.
Weaknesses of Neural and Genetic explanations
✗ Explanations are biologically reductionist - criminality is complex, crime runs in families, but so do poverty, deprivation and mental illness. Makes it difficult to disentangle the effects of genes and neural influences from other factors. In isolation, the explanations are too simplistic.
✗ Biologically determinist - a ‘criminal gene’ presents a dilemma - the legal system is based on the premise that criminals have personal and moral responsibility for their crimes. Only in extreme cases (e.g. diagnosis of mental illness) can someone claim that they were not acting entirely of their own free will. Raises ethical questions about what society does with people suspected of carrying these genes.
Psychological explanations: Eysenck’s theory
Eysenck suggested personality types are innate and based on the nervous system we inherit.
Eysenck’s theory: extraverts
- Extraverts have an underactive nervous system which means they seek excitement and stimulation and engage in risk-taking.
Eysenck’s theory: neurotic
- Neurotic individuals have a high level of reactivity in the sympathetic nervous system. They tend to be nervous, jumpy and over-anxious.
Eysenck’s theory: psychotic
- Psychotic individuals are suggested to have higher levels of testosterone - cold, unemotional and aggressive.
Eysenck’s theory: criminal personality
Neurotics are unstable and prone to overreact. Extraverts seek more arousal and thus engage in dangerous activity. Psychotics are aggressive and lack empathy.
- Criminal behaviour is concerned with immediate gratification.
- High E and N scorers lack ability to learn (be conditioned)
- Personality can be measured using Eysenck’s personality inventory.
