|"Just one more thing ..."|
Wright asked 40 experienced UK detectives (aged 36 to 59; one woman) to look at the photos and sort them into groups, "so that all the crime scenes in a group are similar to each other in some way but different from those in another group." As they sorted the photos, the detectives were asked to speak their thoughts out loud. The task took about one and a half hours.
The detectives tended to sort the crimes into three groups according to their inferences about the nature of the murder as either: a domestic homicide, a crime-related homicide (in which the murder had taken place during the commission of another crime), or a male brawl. Wright found that the detectives readily spun a narrative from the photos, with first clues (e.g. a toppled chair and signs of Christmas decorations) leading to generation of a hypothesis (tension between spouses is often high at Christmas), leading to inferences (this could be a domestic), thus guiding their inquiry plans ("I would be looking at those known to her").
Overall, the detectives made 594 inferences, most of them about the homicide type and the relationship between victim and killer. Using recorded facts from the murders, Wright found that 67 per cent of the detectives' inferences were accurate, 23 per cent were inaccurate and 9.5 per cent were ambiguous or contradictory. More senior detectives made more inferences without losing accuracy.
Three murder scenes were misinterpreted by the majority of the detectives because they made the same kind of inaccurate inferences. For example, one killing involved the victim's dress being pulled up around her neck with most detectives interpreting this as a sexually motivated crime. In fact the woman had been killed by her nephew for financial gain. Another scene was at a disco and many detectives inferred it was the result of a drunken brawl. In fact the killer was having an affair with the victim's wife and the murder was premeditated.
The initial decisions made during what detectives call the "golden hour" of a murder investigation can have huge implications for its success. For this reason it is vital that we learn more about the decision making processes involved. "The findings of this study make the first step at demystifying the notion of detective intuition," said Wright.
Detectives aim to keep an open mind, but this study revealed the ways their past experiences and knowledge lead them to make assumptions. Often times these are correct, but there were instances of systematic errors. Wright suggests that sorting tasks of the kind used in this study could be helpful during training of detectives, to "increase their awareness of the factors that influence their decision making behaviour" and to "enhance [their] knowledge of different types of homicide through exposure to a wide range of cases".
Wright, M. (2013). Homicide Detectives' Intuition. Journal of Investigative Psychology and Offender Profiling DOI: 10.1002/jip.1383
Does a murderer's crime-scene behaviour echo his criminal history?
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
Image from wikipedia.