Criminal - Collection + processing of forensic evidence

Question 1

Forensic evidence + examples (Background)

Answer 1

Biological/scientific evidence which could be used to help convict criminals and hence be used in court

Examples: hair, fingerprints, saliva, blood, bodily fluids, bite marks

Question 2

Motivating factors + examples (Background)

Answer 2

Things that make you want to close a case quickly

Examples: high emotion cases (i.e. murder), lots of evidence, weapons on scene, small areas where people are scared

Question 3

Dror - Forensic processing types (Background)

Answer 3

Top-down: you have evidence about a crime first then you investigate; relies on previous experiences of crimes - big picture then fill in details

Bottom-up: look at evidence first, then build a case/theory about what happened; starts with small details and creates bigger picture

Question 4

Dror - Biases in processing of evidence (Background)

Answer 4

Confirmation bias: giving extra emphasis on/intentionally finding evidence which supports expert’s own theories
Overconfidence bias: experts may believe they are always right, even in the face of contradictory evidence
Need determination perception: arises from a strong desire to solve a particular crime, especially high emotion cases
Selective attention: prior expectation can lead to ‘filtering out’ of ambiguous elements in a print where a ‘close call’ has to be made to create a match

Question 5

Dror - High Emotion Context Experiment (Background)

Answer 5

• 27 university students given pairs of fingerprint images and had to decide whether they matched
• Emotional crime (dead person) in ambiguous match pairs of fingerprints lead to a higher likelihood of finding a match
• Demonstrates need determination perception

Question 6

Brandon Mayfield case (Background)

Answer 6

• Misconviction of Mayfield for a bombing
• Many motivating factors such as recent conversion to Islam, 15 unique matches to fingerprint, high profile high emotion case, ex-army officer
• Shows that fingerprint analysis might not be as objective and accurate as advertised

Fingerprints need at least 12 unique features to be counted as a match.

Question 7

Hall & Player - Aims

Answer 7

To find out whether:
- The written report of a crime affects a fingerprint expert’s interpretation of a poor quality mark
- Whether the fingerprint experts are emotionally affected by the circumstances of the case

Question 8

Hall & Player - Method

Answer 8

• Field experiment with independent measures design
• Carried out in the New Scotland Yard Fingerprint Bureau
• IV: low emotion context or high emotion context
• DVs: whether the p read the crime scene report, whether the fingerprint was a match/not a match (or unidentifiable) and whether p would be confident to present the fingerprint as evidence in court

Question 9

Hall & Player - Sample

Answer 9

• Volunteer sample
• 70 fingerprint experts working for the Met Police Fingerprint Bureau
• Mean length of experience 11 years who had experienced a wide variety of cases

Question 10

Hall & Player - Procedure

Answer 10

• Fingerprint from volunteer was inked onto paper then superimposed onto a £50 note (poor quality)
• Finger mark and corresponding set of fingerprint impressions were then given to ps who were asked to give their expert opinions
• Each p was allowed access to a fingerprint magnifying glass and a Russell comparator

Contexts:
High emotion: allegation of murder
Low emotion: use of a forged £50 to pay for goods

Question 11

Hall & Player - Results

Answer 11

• 57/70 head read the crime scene report, 30 from the high-context group
• 52% of the high-context group (read report) said they were affected, 6% of low-context group
• Around 20% of ps in both groups felt confident in presenting the evidence in court
• Overall final decisions made by the experts were very similar regardless of the emotional context

Question 12

Hall & Player - Conclusion

Answer 12

• Emotional contexts have no effect on the experts’ final opinions about a fingerprint match
• Fingerprint experts are able to deal with analysis in a non-emotional manner
• Further research is needed into the crime in order to convict

Question 13

ACE-V Method (Application)

Answer 13

Analyse: data independently
Compare: to sample you have
Examination/Evaluation: of the evidence thoroughly
Verify: with other analysts

Question 14

Education of juries and forensic examiners (Application)

Answer 14

Juries:
- Let them know the strengths and weaknesses of forensic evidence and it can help people become more wary of it’s vulnerabilites to bias

Forensic examiners:
- Cognitive training in acknowledging and minimising bias
- Could include training in basic psychology that is related to forensic work e.g. aspects of perception, judgement and decision-making

Question 15

Miller - Falsification method (Application)

Answer 15

• Present 6 samples to examiners with 1 being the real fingerprint and 5 comparisons
• Look to discount samples first rather than looking for a match straight away
• Been shown to reduce the number of false identifications