Two Mexican men have been extradited to the United States to face charges in the 2011 shooting death of an Immigration and Customs Enforcement special agent.

Jesus Ivan Quezada Pina and Alfredo Gaston Mendoza Hernandez were ordered held without bail after making their first appearance in federal court in Washington on Monday.

The two were charged in a newly unsealed indictment with killing Special Agent Jaime Zapata and wounding another, Victor Avila, in a February 2011 ambush in San Luis Potosi, Mexico.

The charges bring to seven the number of people charged in the death.

Four other men have pleaded guilty in connection with the killing, admitting being part of a hit squad from the Los Zetas criminal group. A fifth man was extradited last fall and is awaiting trial.