MINNESOTA ? Federal prosecutors filed identity theft charges Friday against a woman who was driving a van that crashed into a school bus in southwestern Minnesota, killing four students.

Olga Marino Franco del Cid, 24, of Minneota, had already been charged in state court with four counts of criminal vehicular homicide. The new charges accuse her of giving authorities a false name and Social Security number after the Feb. 19 crash near Cottonwood.

Right after the crash, Franco identified herself as Alianiss Nunez-Morales, but immigration investigators said they found the real Nunez-Morales in Connecticut. She told them her purse and identification documents were stolen more than six months ago in Puerto Rico, according to an ICE affidavit.

The affidavit alleges that Franco used Nunez-Morales’ Social Security number to get a Minnesota identification card. She is accused of giving the number to two Minnesota companies where she worked.