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Linkage Analysis
Linkage Analysis
Police investigators must often determine whether multiple crimes have been committed by the same offender. In ideal situations, this decision is based on an analysis of physical evidence left at crime scenes, such as DNA, fabric fibers, and/or fingerprints. However, despite what is portrayed in the popular media, such evidence is not always available to be processed (Davies 1991). Given this, the police have had to establish alternative methods for linking serial crimes. One of the most commonly used approaches is behavioral linkage analysis.
When using this form of analysis, an attempt is made to link crimes based on the behaviors that offenders engage in while committing their offenses. Specifically, the goal is to identify patterns of behavior across an offender’s crimes that meet two criteria: behavioural stability and behavioural distinctiveness (Canter 1995).
ACTIVITY
ACTIVITY
What do you think the terms behavioural stability and behavioural distinctiveness mean when it comes to analysing (and comparing) crime scenes? Take a few minutes to try and write a definition for each of these terms
Profiling
Profiling
Definition - "the concept of criminal profiling is defined and described as a technique whereby the probable characteristics of a criminal offender or offenders are predicted based on the behaviours exhibited in the commission of a crime."
"If you want to understand the artist, you have to look at the painting"
"If you want to understand the artist, you have to look at the painting"
ACTIVITY
ACTIVITY
Different uses of colour and form give us distinctly different impressions of what must have been in the artist's head while creating the images. In a similar way, think about acoustic chill vs death metal or the fashion choices people make (yes, that's stereotyping!)
Think about the above statement...
Humans are geared to recognise patterns and make inferences based on partial or incomplete data (think 'stereotypes')- it's part of the human condition.
Have a look at the following images and think about the characteristics or emotional state of the individual who created them...
When we apply this kind of thinking to a crime scene we are making assumptions of the characteristics of the perpetrator based on the evidence and context of the scene itself...
While psychiatrists and psychologists alike had on occasion been brought in on cases (like the Mad Bomber), criminal profiling didn't really take off until the 1970's. It's development was led by the newly formed Behavioural Science Unit (BSU) of the Federal Bureau of Investigation (FBI) to provide investigative assistance to law enforcement in cases of serial homicide or serial rape (Homant & Kennedy, 1998).
The development of profiling is the subject of Netflix's 'Mindhunter' series
Activity
Activity
This activity is speculative - there's no 'right' or 'wrong' answer here, as long as you can justify what you've said with sound logic.
To get you thinking like a profiler, imagine we've gone into someone's home and taken some photos! Based on these, what are your assumptions about the following?
How many people (at least) live here?
Gender(s)
Age(s)
Marital status
Hobbies / Interests / Diet / Politics / Employment Status?
Anything else?
Photos
Photos
Gaming PC - Don't Tread on Me Poster - Collection of Shot Glasses - Large Speakers - Men's Boots - Women's Running Shoes - Overflowing Bin - Dartboard with Joe Biden Photo Attached - Pile of Dirty Clothes - Empty Cans of Energy Drink - Samurai Sword - Lean Whey Protein Powder - Gym Membership Card - 1 Set of Car Keys - Hole Punched in Door
Unlike Hannibal's Will Graham, profilers...
Written in 1980, an article titled “A Psychological Assessment of Crime Profiling” set the bar for criminal profiling. In it, the authors (Ault & Reese) described a case involving a serial rapist who sexually assaulted at least seven women over a 2-year period in an East Coast city. Investigators had no suspects in the case and asked the BSU for help. After examining the evidence gathered by investigators, the BSU advised that the rapes were probably committed by the same person.
They described the offender as a white male, 25 to 35 years of age, divorced or separated, marginally employed, with a high school education. The BSU also gave the opinion that the offender had a poor self-image, lived in the immediate area of the rapes, and probably engaged in voyeurism (was a Peeping Tom).
Three days after receiving the profile, police investigators identified 40 suspects in the neighborhood who met the age criteria. Then, using additional information from the profile, they were able to narrow their investigation to one individual, who was arrested within a week.
According to Ault & Reese, "A crime may reflect the personality characteristics of the perpetrator in much the same fashion as the way we keep and decorate our homes reflects something about our personality”
According to Ault & Reese by analysing the crime scene they might be able to determine...
Race • Sex • Age range • Marital status • General employment • Probable reactions to questioning by police • Degree of sexual maturity • Likelihood that the individual will strike again • The possibility that he or she committed a similar offense in the past • Possible police record
However, they did go on to add that “profiles are not the result of magical incantations and are not always accurate"
In order to create a profile, Ault & Reese suggested that investigators seeking the aid of a profiler should provide the following information:
Complete photographs of the crime scene, including photographs of the victim if it is a homicide.
Complete autopsy, including any results of lab tests done on the victim.
Complete report of the incident, including date and time of offense, location, weapon used (if known), investigators’ reconstruction of the sequence of events, and a detailed interview of any surviving victims or witnesses.
KEY POINT:
KEY POINT:
Profiling isn't about just looking at the crime scene and making assumptions about the characteristics of the offender based on a hunch. It's a game of probabilities - deductions about an offender based on the state of the crime scene have to be backed up by similar cases in the past which have had a successful outcome - i.e., they found the offender. Knowing which features of a crime relate to which personal characteristics is something that has to be learned, for examples, see the case study of John Duffy, aka the Railway Rapist, below.
The Case of John Duffy (The Railway Rapist)
The Case of John Duffy (The Railway Rapist)
David Canter is one of Britain’s leading offender profilers. He was asked to help the police build up a profile of a man who had committed a series of sex attacks and murders.
Based on the gathered evidence the police believed that it was the same man committing these crimes.
Using the information from the police David Canter was able to start to build the offender profile. This evidence consisted of the facts as well as the evidence gathered at the scene...
This information helped David Canter to produce a profile that subsequently led to the arrest of John Duffy. Canter described 17 personality traits of which 12 were completely accurate. Some of these are listed below:
ACTIVITY
ACTIVITY
After watching the video and reading the article below, complete the assignment 'Profiling 1' on Teams
Profilers rely on past instances of similar crimes as well as socio-demographic statistics to deduce characteristics about the perpetrators. Even with abundant cases to compare, profiling is still a game of probabilities.
Use these slides to help you complete the activity...
Additional Resources:
If you've managed to complete this week's assigned work, take a look at these additional resources...
A really interesting chapter on the psychology of investigations. Dr Canter is a big name in profiling and investigative psychology in the UK - he heads up the International Research Centre for Investigative Psychology. There's a whole chapter here but the first 7 / 8 pages should give you a good overview.
A full chapter from a student workbook on criminal profiling including activities. I'm not allowed to download and share the PDF for copyright reasons but I can give you the link to the website from which you can download it yourself.
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