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When detectives in Dallas solved a 20-year cold murder case in early 2020, the celebrations rippled across the Atlantic. Needing verifiable evidence connecting the suspect to multiple murders over many years, the detectives drew a comparatively new UK-developed interview technique into their approach to obtaining information from the suspect.

Called the Timeline Technique, this interview format moves away from the conventional question-and-answer approach and instead requires witnesses to complete a detailed timeline of events. The process reduces reliance by investigators on ‘story’ narratives that gloss over details and place a heavy burden on interviewees’ memories and on the choice or nature of the questions asked.

In empirical tests, the Timeline Technique has been found to elicit a more complete and accurate chronicle of events. The Timeline Technique is part of an innovative set of interviewing and information elicitation tools developed in the UK and informed by psychological science. Another example is the ‘selfadministered interview’ (SAI©), developed by Lorraine Hope, a Professor of Applied Cognitive Psychology at the ���ɱ����ϲ�, with Fiona Gabbert (Goldsmiths, University of London) and Ron Fisher (Florida International University).

The technique is essentially a set of structured questions that witnesses complete by themselves. It was designed to help police capture the immediate memories of eyewitnesses to incidents in public spaces, such as terrorist attacks or other mass incidents.

“It prompts for all the details,” explains Professor Hope. “Then, it probes for information about the people who are involved, who else was present, were vehicles involved, what were the conditions under which you viewed, and so on.”

Professor Hope’s psychology research has come to have a direct impact, both in the UK and internationally, on how law enforcement now gathers evidence. It is an achievement recognised by the International Investigative Interviewing Research Group when it awarded her the 2019 Award for Academic Excellence.

Supporting witnesses

Professor Hope’s work addresses challenges relating to “memory at the sharp end”, when witnesses – including victims, emergency services personnel and passers-by – have critical information needed by law enforcement.

“Memory is not like a video recorder,” she points out. “Physical and psychological demands take their toll on a person’s cognitive resources – as well as factors such as having to make decisions and responses quickly. This means that crucial information may not always be optimally encoded. At other times the information is encoded, but witnesses need help to retrieve it from memory.”

Memory in dynamic encounters

In other research aimed at assessing the effect of psychological stress on memory, Professor Hope monitored heart rates in pairs of police officers – one responding to an increasingly agitated armed offender threatening hostages and officers, and the other officer observing the simulation.

Afterwards, both officers had to give detailed accounts of what had happened. The active responder had a significantly higher heart rate and recalled significantly less correct information about the incident compared to the observer.

Almost 20 per cent of participants in this study recalled the offender pointing a gun at them – something that never happened. This illustrates an interesting and naturally occurring memory error.

Helping when resources are limited

The SAI© provides police with additional options for obtaining reliable information from multiple witnesses at a crime scene. In one of Professor Hope’s case studies, Greater Manchester Police helped test the SAI© after a chaotic road accident in which a speeding motorbike rider had crashed into a car, killing himself and landing his two pillion passengers in the path of an oncoming bus.

The first police officers on the scene identified eight key witnesses, to whom they spoke immediately. They took the names of another eight people who, under normal circumstances, would have been interviewed later. On this occasion, these witnesses were given SAI© forms. The feedback from police was that this saved them considerable time and helped them to identify three more eyewitnesses with useful information.

“Over time, your memory decays,” Professor Hope says. “So witnesses will be losing information from memory, such as valuable, specific details about what they saw. There’s also time for the memory to become contaminated, perhaps by new information about the incident appearing on the news, or false information being spread on social media.”

The SAI© now forms part of the College of Policing’s recommendations for obtaining initial accounts from witnesses in England and Wales. It has been translated into numerous languages and adopted either for use or in trials in Europe and internationally.

The SAI© has also been adapted for use in digital and online formats, while versions for other investigative contexts have also been developed including, most recently, a version to assist with missing persons investigations.

“In psychology, we ought to be able to deliver better tools and techniques for police to provide the best possible accounts of what happened, informed by objective science. There is no judgement in this – it’s all about the evidence,” says Professor Hope.