Linking behaviour to characteristics:
Evidence-based practice and
offender 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 Manual
(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 Homicide
(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
Canonical Equation
(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
Homicide

Sexual 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
(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 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
predictable

Excessive binding, Prolonged Transport, No
negotiation, “Macho”
Evaluation of FBI Rape Typology
(Bennett, Ogloff, & Davis, in prep)
ANGER
POWER
Evaluation of FBI Rape Typology
(Bennett, Ogloff, & Davis, in prep)
ANGER
POWER
Evaluation of FBI Rape Typology
(Bennett, Ogloff, & Davis, in prep)
ANGER
POWER
11%-39%
Evaluation of FBI Rape Typology
(Bennett, Ogloff, & Davis, in prep)
ANGER
POWER
5%-10%
11%-39%
Thematic classification of rape
(Canter, Bennell, Alison, & Reddy, 2003)
Sexual 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, dependent
 Opportunistic: antisocial, narcissistic, paranoid

(Proulx et al., 1994, 1999)
Arson

FBI-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
offender profiling information
Demographic
Characteristics
Offending
Behaviour
Conceptual model of
offender profiling information
Personality
Demographics
Offending
Behaviour
Conceptual model of
offender profiling information
Situational
Influences
Personality
Demographics
Offending
Behaviour
Conceptual model of
offender profiling information
Situational
Influences
Personality
Demographics
Offending
Behaviour
Progress in geographical
profiling 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 directions

Determine 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 directions

Personality (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
Conclusion

Current 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)