Pallbearers carry the casket of ICE agent Jaime Zapata on Feb. 22, 2011. (Delcia Lopez/AP)

By Spencer S. Hsu May 16 at 6:05 PM

Two men accused of killing one U.S. immigration agent and wounding another in Mexico have been extradited to the United States, bringing the total charged in the 2011 incident to seven, U.S. authorities announced Monday.

Jesus Ivan Quezada Piña, 28, a.k.a. “Loco,” and Alfredo Gaston Mendoza Hernandez, 33, a.k.a. “Camaron” and “Burger,” both of San Luis Potosi, Mexico, made their first appearance in federal court in Washington as officials unsealed charges of murder and attempted murder in a four-count indictment from May 2013 in the death of U.S. Immigration and Customs Enforcement Special Agent Jaime Zapata, U.S. officials said.

Zapata was shot to death in an ambush on a highway near San Luis Potosi in north-central Mexico on Feb. 15, 2011. Another ICE special agent, Victor Avila, was wounded but survived.

Senior U.S. District Judge Royce C. Lamberth of the District of Columbia ordered the defendants held without bail pending further hearings.

U.S. authorities in May 2013 announced guilty pleas by Zetas cartel commander Julian Zapata Espinoza, known as “El Piolin,” 35, for leading the attack, and three other members of two alleged drug-cartel hit squads on related charges. All face up to life in prison and await sentencing.

Jaime Zapata’s death, the first in Mexico by a U.S. officer in the line of duty since 1985, highlighted American involvement in the U.S.-backed drug war in Mexico. Monday’s court appearance came one week after a Mexican judge ruled that the world’s most wanted drug lord, Joaquín “El Chapo” Guzmán, can be extradited to the United States following his bloody recapture in January by Mexican security officials after he escaped prison a second time.

A fifth defendant, Jose Emanuel Garcia Sota, 35, a.k.a. Juan Manuel Maldonado Amezcua, or “Safado,” awaits trial after being extradited to the United States in October among a group of 13 defendants that included an alleged former leader of the Gulf and Zetas cartels; two high-level members of the Sinaloa and Beltrán-Leyva cartels; and suspects in a 2010 attack in Juarez, Mexico, that killed a U.S. consulate worker, her husband and the husband of another consulate employee.

“The ICE family is deeply grateful to the Government of Mexico, the Department of Justice, and all of our other partners engaged in the relentless pursuit of the perpetrators of this heartless attack,” ICE Director Sarah R. Saldaña said in a statement with the U.S. Attorney’s Office in Washington, FBI and Justice Department

“An attack against any federal agent serving his or her country remains a priority for the FBI until all responsible individuals are brought to justice,” FBI Assistant Director Stephen E. Richardson said.