Offender Profiling

Background/Aim: To investigate if there is empirical support (a scientific basis) for the organised/disorganised typology classification of serial killers (which originated from ad hoc interviews/ case information on an unrepresentative, opportunity sample of 36 serial murderers who volunteered to talk to FBI agents, with no subsequent test on reliability and with known validity problems).

Sample: 100 cases of serial, sexual homicides committed by 100 US serial killers (known as Missen Corpus data). 

Method: Published Missen Corpus data cross checked with court reports and, where possible investigating officers. Content analysis (which identified 39 different crime 'factors') followed by multi-dimensional scaling test (SSA) of co-occurence of 39 factors. Crimes followed Crime Classification Manual (CCM) in relation to crime scene and offender characteristics (third crime used). 

Results: Twice as many disorganised crime scene actions (26) were identified than organised (13). The frequency of actions/variables varies. Few examples found of co-occuring characteristics considered (previously) to indicate whether crime organised or disorganised. Smallest space analysis (SSA) used to test hypothesis of organsied/disorganised typology (which would predict characteristics would fall into two distinct regions of SSA space) found that disorganised variables are scattered across the display with the organised variables mixed in among them. Ten variables (high-frequency/ in central region of SSA display) that occur in more than 50% of cases are made up of equal numbers of organised and disorgansied variables.

Evaluation: Analysis doesn't validate organised/disorganised typology. Canter proposes different styles of interation (i.e. the need to focus on offender's behaviour) with the victim (e.g. sexual control, mutilation) may be more useful in profiling. The pre-established data base eliminates researcher bias (as does using the CCM), cross-checking of sources and statistical analysis means data generally considered robust/reliable. Statistical analysis eliminates researcher/interpretation bias. Canter attempts to move the way offender profiling is conducted towards scientific procedures that can be checked for reliability, falsifiability and objectivity.

Aim: To identify associations between aspects of the offender's characteristics and offence behaviour using scientific, objective measures.

Sample: 27 sex offenders (and their 66 sexual offences documented by various English police forces, involving sexual assaults against strangers).

Method: Initial exploration of a range of crimes on which full information was available. 33 offence variables were identified through data available ( e.g. victim statements and police report, not collected for research purposes so no detailed protocol or training for data collection). Behavioural variables with low frequencies were excluded (considered of less value here in developing general principles). Variables categorised with yes/no values (i.e presence or absence of behaviour). Content analysis and subsequent Smallest Space Analysis (SSA) ( a multi-dimensional scaling procedure examining relationship between one variable and every other examined, which represents correlation between variables as distances in statistically derived geometric space).

Result: Analysis of factors indicates that there are five variables that are central to **** (vaginal intercourse; no reaction to victim; impersonal language; surprise attack; victims clothing disturbed), which Canter considers as indicative of an impersonal surprise attack. Another constellation of variables - 'attempted intimacy' (e.g. offender requires victim to participate verbally and physically during assault, offender inquisitive about victim and four others); 'impersonal interaction' (e.g. blitz attack, impersonal language, no response to victims reaction and three others) would be predicted to be a reflection of a general approach to women in offenders everyday life (seeing them as sex objects, rather than as people).

Evaluation: Taking a statistical approach to data analysis allowd greater confidene in results, subjective interpretation is eliminated and the findings can be considered more reliable. Small sample (although fairly large number of offences), and restricted crime type. As statistical analysis can be done on different crime types means research potentially useful. Less reductionist as large number of variables/behaviour investigated. Psychology as a science - Canter attempts to move the way offender profiling is conducted towards scientific procedures that can be checked for reliability, falsifiability and objectivity.

Background: Canter became involved in this case in 1985 when the police (convinced that a series of rapes/murders were the acts of one man) asked if he could help catch the man 'before he kills again'. Material was later documented in Canter's Criminal Shadows book. 

Aim: To systematically document crimes, crime scene details, chronology (and subsequently geography) in order to infer possible behavioural characteristics of an offender, using psychological principles/knowledge and scientific methods. Canter calls this Investigative Psychology and believes 1: Crim involves communication between two people. The way the offender behaves towards the victim will reveal something about the offenders dealing with people in everyday life. 2: A systematic/scientific approach is essential, which includes consideration of all available evidence (nothing should be discounted just because it 'doesn't fit'). 3: An offender is likely to commit crime, at least initially, in a familiar area (often called a 'home' range)- this may be where the offender lives/works. Geographical mapping (and timings) of crime can help identify this range.

Method: Systematic data evaluation exercise in order to generate an offende profile. Data obtained from police databases. It isn't a case study in the usual psychological research sense. 

Results: Canter's profile suggested a number of possible characteristics which allowed the police to narrow down their list of 2000 suspects (linked to the crimes by bloody group). Duffy was originally 1505th. Duffy was apprehended and ultimately convicted in 1988 of two murders and five rapes.

Evaluation: Individual explanations of behaviour. Identifying possible characteristics of an offender allows police to narrow down their list of suspects, direct their resources and ultimately apprehend the offender more quickly.