Mitchell Rivard, a Justice Department spokesman, said the case remains under investigation and declined further comment.

Hernandez, 42, was shot by agents in May 2010 at the busy border crossing as he was being returned to Tijuana, Mexico. Mexican President Felipe Calderon joined a chorus of critics who complained of excessive force by U.S. Customs and Border Protection officials, none of whom have been publicly identified.

An autopsy by the San Diego County coroner's office found Hernandez died of a heart attack, with a heart condition and methamphetamine use listed as contributing factors. The autopsy said Hernandez was unresponsive shortly after he was shot with a stun gun, apparently three or four times.

The coroner's report, citing a San Diego police detective, said Hernandez was "agitated and confrontational" after he was detained by Border Patrol agents crossing the border illegally and became "suddenly violent" when his handcuffs were removed at the border crossing.