WASHINGTON – Ignacio Carlos Flores-Figueroa, an undocumented worker from Mexico, made a curious and undeniably bad decision. After working under an assumed name for six years, he decided to use his real name and exchanged one set of phony identification numbers for another.

The change made his employer suspicious and the authorities were called in. The old numbers were made up, but the new ones he bought happened to belong to real people. Federal prosecutors said that was enough to label Flores-Figueroa an identity thief.