Eyewitnesses and the use and application of cognitive theory

ROUTE MAP OF THE CHAPTER Witnesses and victims may hold the only record of a crime and so their evidence can be invaluable to a criminal investigation. This chapter reviews the different types of evidence provided by eyewitnesses. The initial focus is on their ability to describe details of a crime and those involved, plus interviewing techniques that attempt to maximise this information recall. Next, procedures used to identify offenders are examined. In the final part, face-construction systems are outlined along with methods for improving their effectiveness. Eyewitnesses carry out a range of tasks to help the police bring a criminal to justice. They describe what happened during the crime and the people involved. Later, there may be reasonable grounds for the police to believe they know who is responsible for the offence and this person then becomes a suspect. The police may put the suspect into a line-up or identification parade and ask eyewitnesses to see if they recognise the person they saw. If the suspect is picked out, this outcome is taken as evidence that the police have arrested the correct person. The police then spend time building a case to convict the suspect, or dismiss him or her as either there is a lack of evidence to convict, or another person is responsible for the crime. Sometimes, eyewitnesses provide testimony in a court of law. The police may also use the description given by an eyewitness to try to locate the offender using computer searches of previously convicted people. If a suspect cannot otherwise be identified, such as by using CCTV, DNA or other forensic evidence, eyewitnesses may construct a picture of the offender's face, an image called a facial composite. The police will usually circulate this image internally to police staff; if this does not identify the culprit, the image is published on police websites, in newspapers, and on TV news and crime programmes in the hope that a member of the public will recognise the image and ph