MEXICO CITY - A suspect in the killing of a U.S. immigration agent in Mexico has been detained, the Mexican Defense Department said Wednesday.
The department statement gave no details about the detention.
Immigrations and Customs Agents Jaime Zapata and Victor Avila were shot on a federal highway while traveling in the northern state of San Luis Potosi en route to Mexico City on Feb. 15. The area is at the center of a power struggle between two rival drug gangs, the Zetas and the Gulf Cartel.
U.S. Rep. Michael McCaul told Texas Senate members Wednesday that one suspect is Jesus Rejon, a former corporal in an elite Mexican army unit who defected to the Zetas. It was not clear whether Rejon is the person in Mexican custody.
Rejon, 34, is wanted by Mexican and U.S. authorities. The U.S. State Department has offered a reward of up to $5 million for his capture.
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. 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.
Zapata, 32, and Avila were attacked when gunmen forced their sport utility vehicle off the highway. Avila was shot twice in the leg and is recovering in the United States.
U.S. Homeland Security Secretary Janet Napolitano and U.S. Attorney General Eric Holder attended Zapata's funeral Tuesday in his hometown of Brownsville, Texas. Both vowed to continue helping Mexico in its war against drug cartels battling for lucrative trafficking routes into the United States.
The Homeland Security and Justice Departments formed a joint task force led by the FBI to help Mexico find the killers.
President Barack Obama has thanked Mexico's president for capturing a suspect in the murder of a U.S. Immigration and Customs Enforcement agent and the wounding of another.
Obama told President Felipe Calderon that neither the United States nor Mexico could tolerate violence against those who protect and serve the citizens.