Bottom-up approach to offending

What’s the main difference between the bottom-up approach and the top-down approach to offender profiling?

The top-down approach makes inferences in making profiles, whereas the bottom-up approach makes profiles based on actual data.

Who’s responsible for the bottom-up approach?

David Canter - British psychologist

What are the two parts of the bottom-up approach?

1. Investigative psychology

2. Geographical profiling

What are the three main parts of investigative psychology?

Interpersonal coherence

Forensic awareness

Smallest space analysis

Explain interpersonal coherence.

The theory that people are consistent in their behaviour at the crime scene and in everyday life.

Explain forensic awareness.

Offenders’ behaviours may reveal if they have been in trouble with the police before - if they show an awareness of police techniques.

(Eg being careful not to leave finger prints may indicate being in trouble with the police before)

Explain smallest space analysis.

This identifies three different types of offender:

Instrumental opportunistic - committing the crime to accomplish a goal, taking the easiest opportunities

Instrumental cognitive - Planning the crime because of concerns about being detected

Expressive impulsive - uncontrolled, in the heat of strong emotions, may feel provoked by the victim

What is geographical profiling?

Analysing and generalising locations of a series of connected crimes.

It considered where the crimes were committed, special relationships between crime scenes and how they may relate to an offender’s place of residence.

What are the two parts of geographical profiling?

Circle theory

CGT

Explain circle theory.

The theory that offenders have a spatial mindset - they commit their crimes in an imagined circle.

Marauder - the offender’s home is within the geographical area that crimes are committed in

Commuter - the offender travels to another geographical area and commits crimes within a defined space

Explain Criminal Geographic Targeting (CGT)

A computerised system developed by Rossmo.

The system creates a 3D map (called a jeopardy surface) displaying spatial data related to time, distance and movement to and from crime scenes. The different colours on the map indicate likely closeness to the crime scene.

Positive eval

Rossmo (1999) said that geographic profiling can be useful in prioritising house-to-house searches or identifying an area where DNA can be collected.

However point

The bottom-up approach is more scientific than the top-down approach - the use of statistical techniques and computer analysis.

Although, Rossmo’s formula (used to generate jeopardy surface) has been criticised.

Negative eval

Canter and Larkin studied 45 sexual assaults - they identified 91% of offenders to be marauders. This high majority makes the classification not useful.

Petherick (2006) pointed out flaws with CGT - may lead the police to look in the wrong place if the criminal’s home base isn’t at the centre of the circle, also using circles is oversimplified - there may be other shapes.

The bottom-up approach can’t distinguish between multiple offenders in the same area.

Conclusion

Profiling can assist police in narrowing down the field of possibilities, but it can’t be fully relied on - Colin Stagg was thought to be responsible for the murder of Rachel Nickel, the actual murderer was originally ruled out as he didn’t fit the profile.