Julian Zapata Espinoza, one of six members of the Zeta drug cartel, was arrested in a raid in San Luis Potosi.
Immigration and Customs Enforcement agents Jaime Zapata and Victor Avila were driving on Feb. 15 from Monterrey to Mexico City when suspected drug cartel members forced Zapata's vehicle from a roadway and opened fire.
Zapata was killed and Avila was wounded.
A spokesman for the Mexican army said the gunmen claim they mistook the U.S. agent's SUV for a vehicle used by a rival gang.
