on Brandon Mayfield Case
the March terrorist attacks on commuter trains in
Madrid, digital images of partial latent fingerprints
obtained from plastic bags that contained detonator
caps were submitted by Spanish authorities to the
FBI for analysis. The submitted images were searched
through the Integrated Automated Fingerprint Identification
System (IAFIS). An IAFIS search compares an unknown
print to a database of millions of known prints.
The result of an IAFIS search produces a short list
of potential matches. A trained fingerprint examiner
then takes the short list of possible matches and
performs an examination to determine whether the
unknown print matches a known print in the database.
Using standard protocols and methodologies, FBI
fingerprint examiners determined that the latent
fingerprint was of value for identification purposes.
This print was subsequently linked to Brandon Mayfield.
That association was independently analyzed and
the results were confirmed by an outside experienced
Soon after the submitted fingerprint was associated
with Mr. Mayfield, Spanish authorities alerted the
FBI to additional information that cast doubt on
our findings. As a result, the FBI sent two fingerprint
examiners to Madrid, who compared the image the
FBI had been provided to the image the Spanish authorities
Upon review it was determined that the FBI identification
was based on an image of substandard quality, which
was particularly problematic because of the remarkable
number of points of similarity between Mr. Mayfield's
prints and the print details in the images submitted
to the FBI.
The FBI's Latent Fingerprint Unit will be reviewing
its current practices and will give consideration
to adopting new guidelines for all examiners receiving
latent print images when the original evidence is
The FBI also plans to ask an international panel
of fingerprint experts to review our examination
in this case.
The FBI apologizes to Mr. Mayfield and his family
for the hardships that this matter has caused.