In this undated photo released by U.S. Immigration and Customs Enforcement (ICE) on Wednesday Feb. 16, 2011 is seen ICE Special Agent Jaime Zapata. Zapata, on assignment to the ICE Attache in Mexico City from his post in Laredo, Texas, died Tuesday Feb. 15, 2011 when gunmen attacked the agents' vehicle as he and another agent drove through the northern state of San Luis Potosi. The second agent, who wasn't identified, was shot in the arm and leg and was in stable condition, according to statements from the Department of Homeland Security. (AP Photo/ICE)
The department said in a brief statement that one of the suspects in the Feb. 15 killing of U.S. Immigration and Customs Agent Jaime Zapata is in custody.
It gave no other details but said it would provide more information later.
A U.S. law enforcement official familiar with the investigation said Wednesday that authorities have identified a "handful" of people with some connection to the shooting of Zapata on a federal highway in the northern state of San Luis Potosi.
The official, who spoke on the condition of anonymity because he wasn't authorized to discuss the investigation, said the roles of those identified by law enforcement are unclear, but they do have ties to cartels fight to control trafficking in the area.
The Zetas gang has been doing battle with its former ally, the Gulf Cartel in the region.