forensic psychology

offender profiling

method of helping identify the perpetrator of a crime based on the nature of the offence and the manner in which it was committed

case study by FBI

• in depth interviews with 36 convicted sexually orientated murderers.

• collected info from members of the behavuoural sceince unit who were experienced in sexual crimes and homocide.

• info combined data with detailed examinations of cime scene

• evidence used to compare patterns

• organised disorganised

disorganised offender character

 acts are unplanned, impulsive and haphazard

• Socially inadequate individuals

• In an unskilled occupation and lower than average IQ

• Frightened and confused at the time of the murder

• May have sexual dysfunction and past failed relationships

• Live alone and know the victim

• Evidence/ weapon present

• No attempt to conceal the body.

organised

• plan their crimes and victim is targeted

  • Show self-control at the crime scene

  • Are careful to cover their tracks and leave few clues; their victims are strangers or are targeted

  • Intelligent, skilled occupation, socially and sexually competent and married or cohabitating

  • Time of crime depressed or angry, follow crime in media

  • Absence of weapon/ evidence

  • Body is hidden/ evidence from the crime scene

  • Take trophies

constructing FBI profile stages (4)

• data assimilation

• crime lassification

• crime reconstruction

• profile generation

Data assimilation:

Investigators gather together information from multiple sources. e.g. crime scene photos, police reports

Crime classification:

Profilers decide whether the crime scene represents an organised or disorganised offender

Crime reconstruction:

Attempts to reconstruct the crime and generate hypotheses about the behaviours involved

Profile generation:

Profilers construct a 'sketch' of the offender including age range, race, habits, socioeconomic status, personality.

evaluation of typology approach positive

evidence to support the organised category

canter

• 100 us murders

• smallest space analysis 0 statistical technique correlation in behaviours

• revealed subset of eautures

BUT

• little evidence for disorganised

• may exibet both disorganised and organised

• third category

negative for typology sample

• 36 murderers - 25 killers and 11 were single or double murders

• unrepresentative and small to generalised from /

• lack in population validity

• may lie to be socially desirable, deciet.

negative of typology more useful for certain types of crimes.

more useful for - rape arson and cult killing

• cannot be used in theft, burgalary, robbery and assault (not enough known about person)

BUT

• meketa found typology profiling use in burgalary llead to an 85% rise in solved cases in 3 us states.

data driven approach DAVID CANTER. 5 characteristics

• Criminal history 

•  residential location

•  a history of occupation

•   personality characteristics

•  domestic and social characteristics.

data driven what does it do

The data-driven approach identifies the evidence and then tries to formulate relationships between them

Data driven approach

• Offender consistency

• Spatial consistency

• Interpersonal consistency

Interpersonal consistency/cross situational consistency

How the offender interacts with the victim can also demonstrate what the offender is like in everyday life.

john duffy canters profile said need to dominate women and would have fantisies of bondage and rape

accurate as john duffy was convicted of assaulting ex wife.

confident with woman.

• Offender consistency-   

An offender will be consistent in his or her behaviour over time.

john duffy was consistent with crimes as he took keys and tied fingers with twine. modus operandi was consistent.

Geographical profiling (spatial consistency) –

The home acts as a 'centre of gravity' that pulls us back. Where the crimes are committed may indicate where a criminal resides

train station was john duffy, worked on train tracks.

geographical profiling two characters

• marauder and commuter

marauder

 operates close to proximity

commuter

 likely to have travelled a distance away from their usual residence.

evaluation of data driven profiling positive

evidence to support geographical profiling

• 120 american serial killers. smallest space analysis - spatial consistency in behaviour of murderers.

• crime scene has patterns. home acted as centre of gravity

BUT

• cannot be used to capture the offender as it relies on accurate recording of crimes. evidence to suggest that 75% all crimes are not reported,

positive of data driven subjective as in crime scene analysis (more scientific)

• more objective and scientific than typology approach, based on more evidence, psychological theory and statisical analysis. less based on intuitions

• profilers can manipulate geographical, biographical data and psychological data quickly to produce insights and results which assist the investigation.

BUT

• dta inputted into computer may be inaccurate or less accurate as only based on caught offenders. overlooks unsolved crimes.

• used for all sorts of crimes. so more useful.

negative of data driven approach Rachell Nickell

• rachel- stabbed and sexually asulted on wimbledon common in 1992.

• paul britton made profile matched colin stagg.

• real offender robert napper ruled out for being too tall.

profiles can be wrong or misleading and innocent people may be convicted.

BUT

• it can narrow list of potential suspects

negative of data driven approach further,

Copson (95) interviewed 48 police forces and found 83% considered the profile useful, however, they only led to the accurate identification of the offender 3% of the time.

Kocsis et al (2002) chemistry students were able to produce more accurate profiles on a solved murder case than experienced senior detectives.

LIMITED practical value when it comes to solving cases. does not actually lead to identification of the offender.

biological explanations of offending behaviour twin studdies

3500 twins pairs in denmark.

concordance rates for offender behaviour 35% for identical twin males and 13% for non-identical twins.

• checked against danish police records.

• - indicates that behaviour might be inherited

• raymond crowd found that adopted children whose biological mother had criminal record had a 50% risk of having a criminal record by 18 whereas adopted children with no criminal mother was 5%

issue with twin evidence.

• assumes equal environments.

• however, this shared environment assumption may apply more to MZ twins than DZ as MZ twins look the same and people tend to treat them the same this affects behaviour

candidate genes

• 800 finnish offenders

• two genes (MAOA, CDH13)

• MAOA regulates serotonin in brain and linked with aggression. the CDH13 gene has been linked to substance abuse and ADHD)
  - found that 5-10% of all severe crime is attributable to the genes.

critisism of candidate genes

large sample but only from finland - population validity is lacking (ethnocentric)

biologically reductionist to assume this gene leads to crime as doesnt take into account the environment.

SCIENTIFIC MEASURES WERE USED TO ASSESS GENOTYPE SO POSITIVE.

Diathesis-stress model

• said that genetics, biological and environmental factors all interact.

• Does not propose that one or a few genes on their own will determine behaviour.

• Genes are switched on or off by epigenomes, which are affected by the environment

• Support for the diathesis-stress model comes from Mednick et al (1984)

support for diathesis stress model

13000 danish adoptees

neither biological or adopted parents criminals

adopyess that had convictions was 13.5%

20% when either of bio parents had convictions.

24.5 when both adopted or bio parents had convictions

genetic inheritance and environment are important.

neural explanations RAINE BRAIN

41 murders pleading not guilty by reason of insantity

Continuous performance challenge task

Handedness, head injury, ethnicity.

Found a lack of activation in the prefrontal cortex in the sample of murders 

Raine also found abnormal asymmetries in the amygdala and hippocampus (emotional response)

reduced activity in amygdala results in fearlessness

what is the role of the prefrontal cortex.

• focus our attention

• stops us being impulsive

• regulates emotion

• executive part of the brain

• decision making, problem solving, planning

evaluation of RAINE AND HIS BRAIN. postive (useful application+ control group matched pairs)

fish oil/omega 3 which has been shown to reduce violence, it helps with brain function and brain structure.

  

Used a control group that were matched on important characteristics such as schizophrenia. Objective scientific methods were used.

negative of raine and his brain

Correlational and not causation -therefore we cannot establish a cause and effect relationship between reduced activity in the pre-frontal cortex, amygdala and criminality. There may be a third factor which Raine suggested could be environmental.

negative of Raines brains deterministic

those with this gene will be violent, however, not everyone who has the gene may become an offender.

• The criminal justice systems assumes we have free will and make a moral choice. Therefore, there are implications for sentencing if people do not have free will.

antisocial personality disorder as an explanation for offender neural.

Christian Keysers found that only when offenders were asked to empathise (with a person depicted on a film experiencing pain) did their empathy reaction ( controlled by mirror neurones in the brain) activate.

• may have a neural switch that can be turned on and off, unlike the neurotypical brain which has the empathy switch permanently on.