crime 2

• Forensic evidence is information that is collected at a crime scene
• Forensic evidence


  • Fingerprints, blood spatter, boot/shoe/tyre prints, bite marks, hair and fibre samples, DNA, bodily fluids
• Forensic investigation should be objective and scientific; however it is not accurate 100% of the time
• Fingerprints


  Patterns of ridges on the pads of fingers and thumbs, each one is unique
• No two people, not even identical twins, have ever been shown to have identical fingerprints
• Fingerprint analysis


  • Identification of suspects has been greatly assisted by digitally stored fingerprints, international and national databases of people for whom fingerprints are on file and computer programs which enable rapid searching of these databases to find a match for a print lifted from a crime scene
• Forensic science instils in us a confidence that such evidence is collected and analysed both systematically and objectively and provides us with compelling evidence as to the guilt or innocence of suspects
• Fingermark/latent mark


  Fingers leave a trace of this pattern on surfaces we touch, often poor quality, incomplete, smudged, distorted or obscured
• Inked prints


  Marks can be used to determine whether they match the prints of a known suspect - taken in controlled conditions so they are high quality
• Job of a crime scene analyst

  • Fingerprints are analysed and compared by experts, they decide whether the ridge details on the suspect's finger(s) matched those fingermarks collected from the crime scene
• Two fingerprint experts are needed to complete the identification process in order to verify the judgments made and reduce likelihood of misidentifications
• Inter-observer consistency


  Differences between fingerprint examiners

  Difference in one fingerprint examiner over time
• Fingerprint comparison


  An "information processing task" involving processes such as attention and visual searching
• Cognitive bias


  When someone is not accurate or objective about the way they think about something - in this case fingerprint analysis
• Types of cognitive bias

  • Conformity effect, Need-determination perception, Overconfidence bias, Expectancy bias
• Even if experts think that a serious crime has affected their analysis, this does not necessarily mean that it has actually affected their final fingerprint identification decision
• er research suggests that viewing stimuli such as latent marks, cognitive processes are in part determined by unconscious effects i.e. expectations and biases which can detrimentally affect decision-making about matches between prints
• Usefulness


  Wider implications than just fingerprints i.e. hair, DNA. The issues of confirmation biases and emotional context and the corresponding recommendations for improved procedures, may generalise to other practices
• Psychology as a science

  Ways to improve analytical processes in forensics rely on some of the same strategies used to maintain objectivity in psychological experiments
• Analysts


  • Benefit from being 'blind' to key information that could influence the way they collect and interpret their data
  • Another way to reduce bias is to hide the 'real' information among other irrelevant but plausible items, as is done with filler questions designed to hide the key items in questionnaires
  • In forensics, the (potentially) 'real' prints can be presented within the context of similar 'filler' prints
• The suggestions are designed to improve the analysis and ensure it is based on scientific processes
• You need to know:

  • Background – Collection and use of of evidence from witnesses and suspects
  • Key research – Memon and Higham (1999) A review of cognitive interview
  • Application- At least one strategy for police interviews