Forensics: Bottom-Up Approach Flashcards
What does the bottom-up approach start and end with?
- Starts with the evidence from the crime scene.
- Then make scientific and statistical predictions based on the evidence from crime scene and other crimes.
Who created the bottom-up approach?
Canter (1980’s)
What are the two main factors/hallmarks of the bottom-up approach?
Investigative psychology + Geographical profiling
What is investigative psychology?
Process where each crime is recorded onto a database. Then statistical analysis detects patterns of behaviour.
Investigative psychology: How are patterns identified?
Through use of computer databases and a program called Smallest Space Analysis, patterns are identified and it is possible to see if a series of offences are linked.
Investigative psychology: How are the databases helpful/used to find culprit?
Details of each new crime are matched with the database and develop a hypotheses about the likely characteristics, social demographic and motivations of culprit.
What is smallest space analysis?
Statistical technique developed by Canter. Data about many crime scenes and offender characteristics are correlated so that the most common characteristics can be identified.
What study supports the smallest space analysis?
Salfati & Canter (1999) - analysed the co-occurence of 48 crime scenes and offender characteristics taken from 82 murder charges where victim is a stranger. Identified 3 themes.
-Canter and Heritage
What themes were identified by Salfati & Canter
- Instrumental Opportunistic
- Instrumental Cognitive
- Expressive Impulsive
What was the Canter and Heritage study?
Content analysis of 66 sexual assaults - used smallest space analysis.
- Correlations found in patterns of impersonal language and lack of reaction to victim.
- Shows usefulness of how statistical analysis can be used to establish if the same offender is responsible.
What is geographical profiling?
Canter says people reveal themselves in the location they choose as well as behaviour. Assumes offenders are more likely to commit crime closer to them rather than travel (marauder or commuter).
What is a marauder?
An offnerer whose home is within the area the crimes are committed.
What is a commuter?
An offender who travels to another area to commit crime in a defined space.
What theory was created in geographical profiling?
Circle Theory
What is the circle theory?
Canter and Larkin (1993) proposes offenders commit crimes within an imagined circle.
Two types: marauder or commuter.
Describe a commuter offender?
- Commits crimes over large areas.
- Crosses cultural and psychological boundaries.
- Involves complex hunting strategies.
Describe a marauder offender?
- Commits crime within a confined area
- Bounded by psychological barriers and landscape features
- Static, localised
What research supports bottom-up approach?
Copson (1975) - surveyed 48 UK police forces, 75% said profilers advice had been useful.
- But only 3% said it helped catch the offender.
- However the fact it was useful means it saved police time and money.
AO3 points for bottom-up approach?
- Copson study- 75% found it useful suggesting it saved police time + money.
- More holistic than top-down approach - can be related to idiographic and nomothetic.
- Validity - supporting evidence (Rossmo)
- Scientific/statistical database more reliable compared to the top-down.
A03 points against bottom-up?
- Dangers of sticking rigidly to a profile. A profile isn’t fool proof, e.g. Rachel Nickel case.
- Mainly only applied to extreme cases, however is more wide range then top-down.
