Mexican police this week captured a top leader and founder of the feared Zetas drug cartel wanted in connection with the murder of a US federal agent, authorities said.
But previous high-profile arrests have done little to stem the violent crime wave sweeping the country, and on Monday, a day after the capture, 13 gunmen were killed in a firefight with Mexican troops in the volatile northeast.
Police arrested Jesus Enrique Rejon Aguilar, also known as "El Mamito," on Sunday in central Mexico as he was on his way to his mother's house in his home state of Campeche in the south, the Security Ministry said.
Rejon Aguilar, the feared cartel's third-ranking leader, is wanted in connection with a February 14 attack that killed US Immigration and Customs Enforcement (ICE) agent Jaime Zapata and seriously wounded his partner.
The US government has offered a $5 million reward for information leading to the arrest or conviction of those responsible for the killing.
The capture "is a high-level blow to the structure of the criminal group," Mexican national security spokesman Alejandro Poire said Monday.
With the latest arrest, the last remaining original Zetas founder at large is group leader Heriberto Lazcano, Poire said.
According to his criminal file, "El Mamito" joined the Mexican army in 1993 and three years later was recruited into an elite team organized to fight Zapatista guerrillas in the south.
In 1999 Rejon Aguilar and 14 other military deserters formed the Zetas, a group hired to work as hitmen for the powerful Gulf cartel. The Zetas later split from their employers, sparking a bloody turf war.
The Zetas were among the first Mexican crime syndicates to use heavy weaponry and full-scale military tactics, reportedly amassing an arsenal that includes grenade launchers and even ground-to-air missiles.
The Zetas are also accused of two mass killings in Mexico's northeastern state of Tamaulipas and one in the Guatemalan border province of Peten.
The gun battle on Monday in which the 13 gunmen were killed erupted in the Tamaulipas border town of Rio Bravo, when the armed men opened fire on a passing military patrol from inside a house, a military official told AFP.
After the shootout, the soldiers confiscated seven armed vehicles and arrested a man in a nearby home who had an AK-47 assault rifle. The official did not say whether the gunmen belonged to a specific gang.
Earlier on Monday, Mexican forces raided a Zetas camp in Nuevo Leon where they found a stockpile of weapons, including 18 assault rifles.