A Review of the FBI's Handling of the Brandon Mayfield Case, unclassified executive summary. Reason #2

The 2nd. significant factor noted by the OIG was the examiners of some features adjusted or influenced by "backward " reasoning. In effect after determining 10 points of "unusual similarity" the examiners found additional features by working backward from Mayfields file print. The examiners found features in the exemplar and then looked for them in the latent image resulting in "murky or ambiguous details" being erroneously identified as points. When an examiner is dealing with a poor quality latent that lacks clarity, it is tempting to look at the exemplar and work backward but as is clear from the Mayfield case it can have disastrous results. This backward or circular reasoning allowed the examiners in Mayfield to report up to 17 points of identification. A jury or defense attorney presented with a case like Mayfield would be ill equipped to determine that an error had occur ed and then convince a jury of the error.

If you watch any of the shows that highlight current criminal trials ,you'll often hear the analyst talk about having 8 points in fingerprints as a standard, they indicate if there are 8 points the print is an identification. I would suspect many lawyers are under the same impression that if there are 8 points case closed, as we see in Mayfield this is not the case. I would also go back to the point I've made numerous times in the past; the examiners in the Mayfield case all had more training and experience than most examiners testifying in court today. Even highly experienced latent examiners with training can make an identification error, the only way to prevent the error from causing disastrous on sequences is to have the evidence evaluated by an experienced examiner.

Bob McAuley
Dir. Operations/Training
Forensic Biometric Identification Solutions LLC.