Mayfield Error
Definition
The 2004 FBI misidentification of Brandon Mayfield as a contributor to a latent print from the Madrid train bombing, attributed by the DOJ Inspector General review to confirmatory bias during verification; now a reference case study for cognitive-bias training in fingerprint examination worldwide.
- Year
- 2004
- Case
- Madrid train bombing latent print
- Misidentified examinee
- Brandon Mayfield
- Attributed cause
- Confirmatory bias during verification, per DOJ IG review
Common questions
Why is this case still taught in fingerprint training programs?+
It is treated as a landmark demonstration that a highly trained examiner can be led to a wrong conclusion by contextual and confirmation bias, and it prompted procedural reforms around blind verification in latent print examination.
What went wrong at the verification stage specifically?+
The DOJ Inspector General review found that once an initial identification was made, subsequent examiners verifying the match were influenced by knowing the first examiner's conclusion rather than reaching an independent judgment, illustrating why blind verification matters.
Related terms
- Blind Verification
- The procedure in which a second fingerprint examiner independently performs the Analysis and Comparison stages without knowledge of the first examiner's conclusion....
- Confirmation Bias
- The cognitive tendency to search for, interpret, favour, and recall information in a way that confirms or supports one's prior beliefs or...
- Contextual Bias
- The influence of case-relevant background information (suspect financial difficulties, police intelligence) on the direction of an examiner's technical analysis. Demonstrated experimentally for...
- Evaluative Reporting
- A framework for expressing forensic conclusions in terms of the probability of the evidence given the prosecution hypothesis versus the defence hypothesis...
- LIMS Stage Gating
- A laboratory information management system function that prevents an examiner from advancing to the next examination stage until the current stage is...
- Linear ACE-V
- An implementation of ACE-V methodology that enforces strict sequential documentation: analysis of the latent mark must be completed and recorded before the...
- Sequential Unmasking
- An information-sequencing protocol in which the examiner receives the questioned material first, completes and documents the analysis before receiving the known standards,...
- SWGFAST
- Scientific Working Group for Friction Ridge Analysis, Study and Technology; the predecessor body to the OSAC Friction Ridge Subcommittee; produced documentation standards...
- Within-Expert Contradiction
- The finding, documented by Dror and Charlton (2006), that the same examiner can reach contradictory conclusions about the same mark-exemplar pair across...