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PSYC2361

Offender profiling

Using information about an offence, crime scene and victim to infer likely characteristics of the unknown offender and help investigators prioritise suspects.

E1 Main purpose of offender profiling

To narrow and prioritise an investigation. A profile does not identify the offender or establish guilt by itself.

E1 When is offender profiling most useful?

When an offender is unknown, particularly in serious or serial offences where ordinary investigative methods have not yet identified a suspect.

E1 Core assumption behind offender profiling

Behaviour during an offence may contain information about the characteristics, experiences or location of the person who committed it.

E1 Major approaches to offender profiling

FBI Criminal Investigative Analysis and David Canter's Investigative Psychology are the two major approaches covered in the course.

E1 What does FBI Criminal Investigative Analysis try to infer?

The offender's characteristics and likely psychological motivation from features of the crime.

E1 FBI Criminal Investigative Analysis sequence

WHAT → WHY → WHO. Examine what happened, infer why it happened, then infer who is likely to have done it.

E1 Origins of FBI Criminal Investigative Analysis

It developed from FBI investigative experience and interviews with a relatively small group of convicted sexual murderers.

E1 Major limitation of the original FBI research base

The offenders were convicted volunteers from a narrow group, their memories may have been inaccurate, and they may not represent offenders generally.

E1 Organised offender

Claimed to plan offences, bring and remove a weapon, use restraints, control evidence and show greater social competence and average or higher intelligence.

E1 Disorganised offender

Claimed to show little planning, use weapons available at the scene, leave evidence behind and display poorer social competence and lower intelligence.

E1 Mixed offender

An offender or crime scene showing both organised and disorganised features, potentially because plans were disrupted, the victim resisted or the offender's method was changing.

E1 Main problem with organised and disorganised categories

Real offences may not fall neatly into one type, and broad categories can encourage investigators to treat probabilistic claims as facts.

E1 Modus operandi or MO

The functional method an offender uses to commit an offence. It may change as the offender learns or circumstances change.

E1 Signature

Behaviour not necessary to complete the offence that is proposed to satisfy a psychological need and may sometimes help link offences.

E1 Staging

Deliberately changing a crime scene to mislead investigators about what occurred.

E1 Washington sniper case lesson for profiling

Different profilers made inconsistent predictions from the same crime information, showing that confident profiles may disagree and should not be treated as identification evidence.

E1 Pinizzotto and Finkel 1990 sample

Twenty-four people, comprising six professional profilers, six experienced detectives, six clinical psychologists and six students.

E1 Pinizzotto and Finkel 1990 method

Participants examined information from a solved homicide and a solved sexual offence, wrote offender profiles, answered objective questions and ranked possible suspects.

E1 Pinizzotto and Finkel 1990 written-profile result

Professional profilers produced richer profiles and made more accurate predictions in their written reports than the comparison groups.

E1 Pinizzotto and Finkel 1990 objective-test result

Profilers showed a clear advantage on multiple-choice and suspect-ranking measures for the sexual offence, but not for the homicide.

E1 Pinizzotto and Finkel 1990 reasoning result

There was no evidence that profilers processed the case information in a qualitatively different way from non-profilers.

E1 Pinizzotto and Finkel 1990 overall conclusion

Profiler expertise may help in some tasks and cases, but profilers are not consistently superior across offences.

E1 Major profiling problem shown by Pinizzotto and Finkel

An offender may not fit the usual base-rate characteristics, so a profile based on the typical offender can be wrong for a particular case.

E1 Investigative Psychology

David Canter's approach that uses systematic analysis of criminal behaviour to infer offender characteristics and often likely location.

E1 Investigative Psychology sequence

Primarily WHAT → WHO. It focuses on observable actions and their statistical associations with offender characteristics rather than first explaining psychological motivation.

E1 Key difference between FBI profiling and Investigative Psychology

The FBI approach places more emphasis on characteristics and motivation, while Investigative Psychology relies more on systematic behavioural data and statistical relationships.

E1 Strength of Investigative Psychology

It commonly uses larger datasets, transparent statistical methods and peer-reviewed research rather than relying mainly on intuition and individual case experience.

E1 Main limitation of Investigative Psychology

Statistical associations are probabilities rather than rules, so an individual offender can be an outlier.

E1 Canter's five factors

Interpersonal coherence, time and place, forensic awareness, criminal career and criminal characteristics.

E1 Interpersonal coherence

The offender's way of interacting with a victim may reflect their usual interpersonal style outside the crime.

E1 Time and place factor

The timing and location of offending may reveal familiarity, routine, access, confidence or information about the offender's base.

E1 Forensic awareness

The offender's knowledge of evidence collection and attempts to avoid detection, such as removing or concealing forensic evidence.

E1 Criminal career factor

Offenders may show behavioural consistency across offences, while changes in method can reflect learning or reactions to earlier difficulties.

E1 Criminal characteristics factor

Features of an offence can be compared with patterns from similar crimes to make cautious inferences about the offender's background and characteristics.

E1 Salfati and Canter 1999 sample

Eighty-two solved British stranger homicides, each involving one offender and one victim.

E1 Salfati and Canter 1999 method

Police files were coded for crime-scene actions and offender and victim characteristics, then statistical analysis examined which behaviours tended to occur together.

E1 Salfati and Canter 1999 three themes

Expressive impulsive, instrumental opportunistic and instrumental cognitive.

E1 Expressive impulsive homicide theme

Aggression is primarily directed at hurting the victim and may involve multiple injuries or different forms of violence.

E1 Instrumental opportunistic homicide theme

Violence occurs in pursuit of another goal and the victim or opportunity is used to obtain something such as property or sex.

E1 Instrumental cognitive homicide theme

The offence shows more planning, control or concealment, such as removing evidence or hiding or moving the body.

E1 Salfati and Canter 1999 classification result

Only 53 of the 82 cases, about 65 percent, showed a clearly dominant theme, meaning many offences did not fit neatly into one category.

E1 Salfati and Canter 1999 offender associations

Expressive impulsive scenes were associated with histories such as violent or sexual offending, while instrumental cognitive scenes were associated with features such as previous imprisonment or military service.

E1 Salfati and Canter 1999 conclusion

Crime-scene behaviours can form meaningful statistical patterns linked to offender characteristics, but the associations should be used to prioritise suspects rather than treated as deterministic rules.

E1 Geographic profiling

Using the locations of linked offences to estimate areas where an offender may live, work or otherwise be based.

E1 Main purpose of geographic profiling

To prioritise geographical search areas rather than directly identify a particular person.

E1 Least-effort principle

When two options are otherwise equally attractive, people tend to choose the option requiring less effort.

E1 Distance decay

The general tendency for offending frequency to decrease as distance from an offender's base increases.

E1 Buffer zone

An area immediately around an offender's home or base where offending may be reduced because recognition risk is high.

E1 Mental map

An internal representation of an area developed through home, work, transport and leisure experiences that influences where a person feels familiar or comfortable.

E1 Marauder

An offender who operates outward from a home base located within the general offence region.

E1 Commuter

An offender who travels away from home to another region and commits offences within that separate area.

E1 Canter and Larkin 1993 sample and method

They analysed the residence and offence locations of 45 British male serial sexual assaulters who had committed at least two offences.

E1 Canter and Larkin 1993 main finding

About 87 percent were classified as marauders and the offender's home fell inside the offence circle in about 91 percent of cases.

E1 Canter and Larkin 1993 distance finding

Distance travelled from home was very strongly related to distances among offence locations, with a correlation of about .93.

E1 Meaning of Canter and Larkin's findings

Serial sexual offenders often offended in spatial patterns related to their home base, but this pattern should not automatically be generalised to every offender or crime type.

E1 Meaney 2004 finding

The proportion classified as marauders differed greatly by offence type, about 35 percent for burglars and 93 percent for sex offenders in the course example.

E1 What does Meaney 2004 show?

Spatial assumptions vary by offence type, so geographic profiling rules cannot be applied blindly across different crimes.

E1 What does Rossmo suggest is needed for useful geographic profiling?

Roughly five distinct and accurate linked crime locations, reasonable confidence that the same offender committed them, and an assumption that the offender's base has remained reasonably stable.

E1 Major data problem in geographic profiling

Missing offences, incorrectly linked offences or an offender who has moved can distort the apparent spatial pattern.

E1 Why can victim availability override distance decay?

An offender may travel farther because the desired type of victim, setting, escape route or opportunity is only available in certain places.

E1 Can geographic profiling be reliable from one offence location?

No. One point does not provide the spatial pattern needed to estimate an offender's base.

E1 Best way for investigators to use any profile

Treat it as a set of testable hypotheses, keep alternative explanations active and check it against independent forensic, witness and victimology evidence.

E1 Main danger of overconfidence in profiling

Investigators may narrow attention too early, ignore evidence that conflicts with the profile or exclude the actual offender because they do not fit the predicted type.

E1 Jenker case profiling lesson

Precise claims about the offender's sex, age or criminal history go beyond what the available crime scene evidence can establish and should remain provisional.

E2 Central lesson about eyewitness memory

Memory is reconstructive rather than a complete video-like recording, so errors can arise during perception, storage and retrieval.

E2 Why are eyewitness errors especially important?

A confident eyewitness can appear highly persuasive even when their memory or identification is inaccurate.

E2 Lydell Grant case lesson

Multiple independent eyewitnesses can confidently identify the same innocent person, so agreement and confidence do not guarantee accuracy.

E2 Brigham and Bothwell 1983 method

Prospective jurors read descriptions of actual eyewitness studies and predicted how accurately witnesses would identify perpetrators.

E2 Brigham and Bothwell 1983 Study 1 result

Participants predicted about 70.6 percent identification accuracy, while actual accuracy was only 12.5 percent.

E2 Brigham and Bothwell 1983 conclusion

People substantially overestimate eyewitness identification accuracy, so common-sense beliefs about eyewitness memory can be misleading.

E2 Change-blindness car demonstration lesson

Perception is selective and reconstructive, meaning eyewitness errors can begin before information has even been successfully encoded into memory.

E2 Encoding

The initial perception and registration of information when an event occurs.

E2 Storage

The retention of information over time after an event has been encoded.

E2 Retrieval

Accessing stored information when trying to remember an event.

E2 Estimator variable

A factor that influences eyewitness memory but cannot be controlled by the criminal justice system after the event has occurred.

E2 Examples of estimator variables

Viewing duration, stress, quality of view, cross-race or other demographic differences, disguise or appearance changes and whether the face was seen from multiple angles.

E2 Is the type of question asked during an interview an estimator variable?

No. Interview questioning can be controlled by investigators, so it is not an estimator variable.

E2 Weapon focus effect

The presence of a weapon can draw attention away from the offender and impair memory for features such as the offender's face.

E2 Threat explanation of weapon focus

Witnesses focus attention on the weapon because it represents a source of danger.

E2 unusualness explanation of weapon focus

An unexpected or unusual object attracts attention away from other aspects of the scene.

E2 Fawcett and colleagues 2011 study type

A meta-analysis combining previous weapon-focus research.

E2 Fawcett and colleagues 2011 conclusion

The evidence supported contributions from both threat and unusualness, and a weapon-focus effect was found across simulated and real events.

E2 Would weapon focus automatically make an eyewitness inaccurate?

No. Its size depends on other factors such as threat, viewing opportunity, event duration and delay before retrieval.

E2 Situation expected to produce a weak weapon-focus effect

A low-threat situation in which the weapon is common or expected, because it is neither highly threatening nor especially unusual.

E2 Maycock 1995 finding

Drivers appeared to forget about 30 percent of crashes per year, with forgetting still occurring for crashes involving injuries.

E2 Main implication of Maycock 1995

Even major and personally important events can be forgotten, so emotional significance does not guarantee permanent memory.

E2 Misinformation effect

Post-event information can become incorporated into a person's memory and alter what they later report remembering.

E2 Common real-world sources of misinformation

Media reports, conversations with co-witnesses, police questioning and other information encountered after the event.

E2 Blank and colleagues 2013 method

Participants watched a short CCTV jewellery-store robbery, then discussed it with a confederate who introduced inaccurate details before later being tested on their memory.

E2 Blank and colleagues 2013 conclusion

Participants often incorporated the co-witness's misinformation into their later memory.

E2 Did warning participants that the co-witness might be wrong completely remove the misinformation effect?

No. A warning did not fully protect their memories from contamination.

E2 Morgan and colleagues 2013 method

Military personnel experienced a highly stressful prisoner-of-war simulation involving an interrogator and were later exposed to misleading identification information.

E2 Morgan and colleagues 2013 result

Misinformation caused some participants to identify the wrong person as their interrogator.

E2 Importance of Morgan and colleagues 2013

It shows that misinformation can distort memory even for highly stressful and personally experienced events.

E2 Loftus and Palmer 1974 method

Participants watched films of car crashes and received questions using different verbs, such as whether the cars hit or smashed into one another.

E2 Loftus and Palmer 1974 speed result

More forceful wording such as smashed produced higher estimates of vehicle speed.

E2 Loftus and Palmer 1974 false-memory result

Participants given the word smashed were later more likely to remember broken glass even though no broken glass had appeared.

E2 Main lesson from Loftus and Palmer 1974

The wording of a retrieval question can reconstruct memory and produce false details even without explicitly giving the witness a false fact.

E2 Why should leading questions be avoided?

They can influence retrieval and introduce information or assumptions that become incorporated into the witness's account.