Bottom-up approach for offender profiling

bottom-up approach

A British method of offender profiling that aims to create data-driven profiles about an offender using evidence from the crime scene. Does not use pre-determined typologies. Generates hypotheses about an offenders:

1. likely background

2. routine

3. social and psychological characteristics

More scientifically grounded, using theories and methods such as investigative psychology and geographical profiling

Investigative psychology

A key aspect of the bottom-up method, investigative psychology, applies statistical techniques and psychological theory to the analysis of crime scene data to:

• Identify patterns in behaviour across crimes

• Match crime details to a database of similar cases

• Link cases through case linkage

  Key concepts in Investigative Psychology:

1. Interpersonal Coherence

   • Offenders’ interactions with victims may reflect everyday relationships

E.g., Dwyer (2001): Some rapists humiliate victims, others show remorse — this tells us about their interpersonal style.

1. 2. Significance of Time and Place

   • Crime timing and location provide clues about an offender’s routine and base.

   3. Forensic Awareness

   • Some offenders show signs of covering their tracks, suggesting prior police experience.

geographical profiling

Developed alongside investigative psychology, geographical profiling focuses on the spatial behaviour of criminals, especially in serial offences.

• Based on the principle of spatial consistency: criminals commit crimes in familiar areas.

• Helps establish a "centre of gravity" that reveals the offender’s likely home base.

🔄 Canter’s Circle Theory (Canter & Larkin, 1993):

• Marauders: commit crimes close to home

• Commuters: travel to commit crimes away from home

This pattern can help police determine if the offender is:

• Operating within their known area (marauder)

• Travelling (commuter)

• Planning or acting on opportunity

• Possibly indicating age, employment, transport use

example of geographical profiling working in real life

• David Canter helped catch John Duffy, the "Railway Rapist", who committed 24 sexual assaults and 3 murders near rail stations in London.

• Canter’s geographical and psychological analysis led to a profile that matched Duffy very closely — aiding in his arrest and conviction.

Evidence for Investigative Psychology + counterpoint

• Canter & Heritage (1990) analysed 66 sexual assault cases using smallest space analysis.

• Found consistencies across crimes (e.g., impersonal language, lack of victim reaction).

• Showed each offender had a distinct behavioural pattern.

🧠 Supports the core idea of behavioural consistency and validates case linkage.

COUNTERPOINT

These databases rely on solved crimes. Unsolved crimes may be unlinked simply because they’re more complex — a circular reasoning problem.

Evidence for Geographical Profiling

• Lundrigan & Canter (2001): Studied 120 murder cases.

• Found that offenders often dispose of bodies in a pattern forming a ‘centre of gravity’ — their home base.

• Most consistent among marauders (short-distance offenders).

🧠 Strong support for spatial consistency, a key part of the bottom-up model.

Geographical Data May Be Incomplete or Inaccurate

Geographical Data May Be Incomplete or Inaccurate

• Ainsworth (2001): Success of profiling relies on quality of police data.

• Crime recording varies between regions, and 75% of crimes go unreported – “the dark figure of crime.”

🧠 Weakness: If the base data is flawed, so is the profile.

Mixed Effectiveness in Real Life

• Copson (1995): Surveyed 48 police forces:

  • Profiling was “useful” in 83% of cases

  • But led to correct identification in only 3% of cases

• Rachel Nickell case: A tragic example where profiling misled the investigation.

• Kocsis et al. (2002): Found that chemistry students created better profiles than experienced detectives in some solved cases.

🧠 Suggests profiling can be helpful, but it is not reliably accurate — and may misdirect investigations if relied on too heavily.