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Published on: July 17, 2021
How often do fingerprint examiners disagree in routine casework?
Ruby O'Connor1, Andrew Chapman2
1NSW Police Force, Forensic Evidence & Technical Services Command, Fingerprint Operations Branch, 1 Charles Street, Parramatta, NSW 2150, Australia; Centre for Forensic Science, University of Technology Sydney, Level 4, Building 4, UTS City Campus, Cnr Harris and Thomas Streets, Broadway, NSW 2007, Australia.
Fingerprint expert casework decisions show high unanimity, with disagreements often stemming from subjective assessments of friction ridge skin impressions. Utilizing computer tools could help reduce these differences in opinion.
Area of Science:
- Forensic Science
- Friction Ridge Analysis
- Expert Decision-Making
Background:
- Prior research indicates expected differences of opinion among fingerprint examiners.
- The representativeness of these findings in routine casework remains uncertain.
Purpose of the Study:
- To analyze differences of opinion between fingerprint experts during routine casework.
- To quantify the frequency and nature of disagreements in fingerprint identification and inconclusive decisions.
Main Methods:
- Analysis of 5000 job-cards from fingerprint experts at the NSW Police Force.
- Scrutiny of 19,491 casework decisions, focusing on expert-to-expert disagreements.
Main Results:
- Expert decisions were unanimous in 94.8% of cases.
- Expert-to-expert disagreements occurred in 3.7% of verification decisions, with higher rates for inconclusive than identification decisions.
- Disagreements were more frequent with trainee decisions than expert decisions.
Conclusions:
- Subjective differences in assessing friction ridge impression suitability are a primary cause of casework disagreements.
- Expert decision-making in fingerprint analysis exhibits inherent subjectivity.
- Computer-based tools, such as quality metrics and likelihood ratio systems, are recommended to guide evaluations and mitigate disagreements.
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