On 11 March 2004, terrorists in Madrid, Spain detonated bombs on several commuter trains. In total, 191 people were killed and 1,400 were injured. After the bombing, examiners from the Federal Bureau of Investigation (FBI) identified a latent fingerprint found on a bag containing detonators and explosives as coming from an Oregon lawyer named Brandon Mayfield. Mayfield was arrested and held as a material witness for two weeks, until the Spanish National Police determined that the print did not, in fact, come from Mayfield, but from another man living in Spain
