Linking behaviour to characteristics: Linking behaviour to characteristics: Evidence-based practice and Evidence-based practice and

offender profilingoffender profiling

Michael R. Davis

School of Psychology, Psychiatry, and Psychological Medicine, Monash University, Australia

and

Victorian Institute of Forensic Mental Health (Forensicare)

“Let me make it very clear, poor people aren’t necessarily

killers.

Just because you happen to be not rich doesn’t mean you’re

willing to kill”

- George W. Bush (May 19, 2003)

Crime Classification ManualCrime Classification Manual(Douglas, Burgess, Burgess, & Ressler, 1992)(Douglas, Burgess, Burgess, & Ressler, 1992)

Homicide, Arson, Sexual Assault– Detailed DSM-type classification– Potential profile information

“At present there have been no systematic efforts to validate these profile-derived classifications” (p. 22)

“We want to emphasize…that this rationally derived system has not yet been…tested” (p. 22)

Sexual HomicideSexual Homicide(Ressler et al., 1986, 1988)(Ressler et al., 1986, 1988)

Organised/Disorganised - 36 murderers interviewed

Organised– Scene: planning, controlling, sexual acts with live victim– Offenders: intelligent, skilled job, angry & depressed

Disorganised– Scene: position dead body, necrophilia, depersonalisation– Offenders: low birth-order, know victim, confused, live alone

Problems with statistical analyses

Profiling expressed as a Profiling expressed as a Canonical EquationCanonical Equation(See Canter, 1995; Youngs, 2004)(See Canter, 1995; Youngs, 2004)

B1A1 + B2A2 + … + BnAn = D1C1 + D2C2 + … + DnCn

Where:

A = Actions during offences

C = Characteristics of offender

B and D = weightings

= Organized

= Disorganized

HomicideHomicideSexual homicide of elderly (Safarik et al., 2000, 2002)

– White victims more likely to be attacked by black offenders– Race, age, distance from house predictable (approx 70% accuracy)

Sexually-oriented child homicide (Aitken et al., 1995)

– Age, previous convictions, victim-offender relationship predictable– Classification rate > 70%

U.S. Serial killings (Hodge, in press)

– SSA (thematic structure of crime scene actions)– Themes of offender-victim interaction– Victim viewed as an object, vehicle, or person

Stranger Homicide Stranger Homicide (Salfati, 2000a, 2000b; Salfati & Canter, 1999)(Salfati, 2000a, 2000b; Salfati & Canter, 1999)

Instrumental and expressive offence actions

Three themes (65% classified)– Expressive (impulsive)

Married, previous violent, property, sexual, & drug offences

– Instrumental (Opportunistic) Previous offences for burglary, unemployed, familiar with area

Finnish Stranger Homicides (Santtila et al., 2003) Instrumental offenders unlikely to confess

Sexual AssaultSexual Assault

FBI rape typology (Warren et al., 1991)

– Power and anger motivations– Behaviour classified as proposed by typology

(71-91% of cases)– Increased violence in subsequent rapes

predictableExcessive binding, Prolonged Transport, No

negotiation, “Macho”

Evaluation of FBI Rape TypologyEvaluation of FBI Rape Typology(Bennett, Ogloff, & Davis, in prep)

ANGER POWER

Evaluation of FBI Rape TypologyEvaluation of FBI Rape Typology(Bennett, Ogloff, & Davis, in prep)

ANGER POWER

Evaluation of FBI Rape TypologyEvaluation of FBI Rape Typology(Bennett, Ogloff, & Davis, in prep)

ANGER POWER

11%-39%

Evaluation of FBI Rape TypologyEvaluation of FBI Rape Typology(Bennett, Ogloff, & Davis, in prep)

ANGER POWER

11%-39%

5%-10%

Thematic classification of rapeThematic classification of rape(Canter, Bennell, Alison, & Reddy, 2003)(Canter, Bennell, Alison, & Reddy, 2003)

Sexual AssaultSexual Assault

Links with characteristics– History of burglary (Canter et al., 1991; Davies et al., 1998)

– Higher levels of violence in rape linked to personality disorder

Sadistic: schizoid, avoidant, dependentOpportunistic: antisocial, narcissistic, paranoid(Proulx et al., 1994, 1999)

ArsonArsonFBI-motivational typology (Icove & Estepp, 1987)

– Classification supported by 1016 interviews

Empirical classification – four themes (Canter & Fritzon, 1998; Fritzon, 1998; Fritzon et al., 2001)

– Instrumental and expressive arson– Person or object focussed– Four corresponding themes of background characteristics

– Supported in active case (Santtila et al., 2003)

Conceptual model of Conceptual model of offender profiling informationoffender profiling information

Demographic Offending

Characteristics Behaviour

Conceptual model of Conceptual model of offender profiling informationoffender profiling information

Personality Offending

Behaviour

Demographics

Conceptual model of Conceptual model of offender profiling informationoffender profiling information

Situational

Influences

Personality Offending

Behaviour

Demographics

Conceptual model of Conceptual model of offender profiling informationoffender profiling information

Situational

Influences

Personality Offending

Behaviour

Demographics

Progress in geographical Progress in geographical profiling is more rapidprofiling is more rapid

Data is more precise

Attack or disposal sites are obviously influenced by the situation, but less so than interpersonal behaviour

Theoretically barren use of demographics is not a component of the calculations

Future research directionsFuture research directionsDetermine offence behaviours least influenced by

situational factors– Respondent vs operant behaviour

(Funder & Colvin, 1991; McClelland, 1984)

Focus on personality traits– Hypotheses from existing SSA plots

Causal-theoretical statistics

– Interviews with offenders

Well-validated personality inventories Determine conditional traits (Alison et al., 2002; Wright & Mischel, 1987)

Future research directionsFuture research directionsPersonality (Youngs, 2004)

– 207 young offenders– Delinquency and personality questionnaires – Expressive/instrumental and person/property distinction– Expressive-person related to power and control– Property offenders perceived more controls from others– Offenders targetting people perceived more emotional closeness

Decision-making in individual profiles– Determine situations where research is inaccurate– Beneficial for theory development

ConclusionConclusionCurrent empirical literature

– Broad demographic features & themes of interaction

Purely actuarial approach not feasible

“Structured Professional Judgment” (Davis, 2003) – Use empirical evidence to anchor & inform judgment– Add to & vary opinion based on case-specific features– Base variations on theory or clearly explained

deduction (rather than intuition)

Clear parallels with pragmatism (Alison, 2005)