Behavioural Distinctiveness
Definition
The property that the consistent behaviours in question are rare enough across unrelated offenders that shared possession of them cannot easily be attributed to coincidence; the second necessary condition for linkage inference.
- Applies to
- Serial offending behaviour patterns
- Role
- Second necessary condition for linkage inference
- Paired condition
- Behavioural consistency
- Function
- Rules out coincidental shared behaviour
Common questions
How is distinctiveness actually established rather than assumed?+
Analysts compare the frequency of the behaviour in a reference sample or database of unrelated offences of the same crime type, so a claim of distinctiveness rests on base-rate data rather than the analyst's subjective sense that a detail seems unusual.
What is an example of a behaviour that fails the distinctiveness test even though it is consistent?+
Wearing gloves or wiping surfaces for fingerprints appears across many unrelated burglars and is consistent within an offender's series, but it is common enough across the wider offender population that its presence alone offers weak support for linking two specific cases.
Related terms
- Behavioural Consistency
- The tendency of a serial offender to repeat the same distinctive behaviours across multiple offences; one of the two necessary conditions for...
- Linkage Analysis
- The investigative and forensic method of determining whether two or more crimes were committed by the same person, based on the presence...
- Modus Operandi (MO)
- The functional, learned behaviours the offender uses to commit the offence: how to gain entry, control the victim, complete the act, and...
- ROC / AUC Analysis
- Receiver Operating Characteristic / Area Under the Curve analysis; the statistical method used to measure the discriminative accuracy of a linkage system,...
- Signature
- Psychologically expressive behaviours that go beyond what's needed to complete the offence: posing the body, ritual acts, taking trophies, leaving messages. Signature...
- ViCLAS
- Violent Crime Linkage Analysis System; the RCMP-developed database capturing 168 behavioural and physical fields from serious violent crimes in Canada and adopted...