Mexican marines arrested the boss of the country’s cruelest drug cartel early Monday, a triumph for the Mexican government even as the bloody drug war shows few signs of slowing. Miguel Angel Treviño Morales, the notorious leader of the Zetas cartel, was apprehended, without firing a shot, in a pickup truck along with two companions near the Mexico-U.S. border. Marines found in his possession eight assault weapons and 500 rounds of ammunition, in addition to $2 million in cash.

The drug lord is linked to the deaths of hundreds of migrants and charged with drug trafficking, murder and torture, among other things, a government spokesperson said, according to the Guardian. The U.S. had also issued a $5 million reward for information leading to his arrest following charges of drug trafficking and weapons possession, though it is unclear what, if any, role the U.S. played in Treviño Morales’ capture.

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The Mexican drug war, which has cost the lives of more than 60,000, is nearing its seventh year since the federal army began combatting the numerous cartels that export billions of dollars worth of drugs to the U.S. annually. The capture of Treviño Morales provides President Enrique Peña Nieto with his most significant victory since he took office in December. At the time, he promised to shift away from the overly militarized strategies of previous President Felipe Calderón, but, like his predecessor, he has struggled since to stem the tide of violence.

Authorities have killed or captured at least eight prominent members of the Zetas, a leading perpetrator of such violence, according to the AP. Treviño Morales’ predecessor at the top, Heriberto Lazcano, was reportedly killed in a shoot-out with the Mexican navy last year.

The Zetas organization originated as a paramilitary branch of the Gulf cartel, one of the oldest crime groups in the country, which recruited initially from the disaffected ranks of Mexico’s elite special forces. Ioan Grillo, a TIME contributor and author of El Narco, a look at Mexico’s devastating drug cartels, writes in his book that by 2010 the newly independent Zetas were estimated to have more than 10,000 soldiers and had expanded beyond Mexico’s borders.

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A 2007 trial into the execution-style murder of five men in East Texas exposed the breadth of the Zetas’ reach. The Mexican cartel has also staked out a claim on the drug trade in Guatemala, where it has committed similar atrocities and fought similar battles with law enforcement as the ones waged in Mexico. The Zetas have garnered a name for themselves as the most notorious of Mexico’s drug cartels, associated with torture, beheadings and mass kidnappings.

In two separate incidents in San Fernando, members of the Zetas kidnapped a total of 265 migrants traveling through their territory — a commonplace Zetas method of extorting even small sums of money — and then proceeded to massacre all of them.

“Violence was no longer a way of control but a basic language of communication. They committed atrocities that made even seasoned cartel bosses sick,” Grillo writes. “They had gone beyond the pale.”

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Treviño Morales, who was the national commander of the Zetas at the time of the massacres, was as brutal a leader as any. The AP reports that the guiso, or stew, was a favorite torture technique of his — victims are placed in a 55-gal. drum and burned alive.

The 40-something-year-old commander, known within the organization by his alias Z-40, did not start out in the Mexican elite force where much of the Zetas leadership was trained — often with support from U.S. or Israeli special forces. Instead, Treviño Morales joined up with the Gulf cartel in his hometown of Nuevo Laredo, a city just across the border from Laredo, Texas, that is now considered the base for the Zetas. He rose up through the ranks and, in 2005, led the Gulf cartel and its paramilitary wing, the Zetas, in a successful turf war in Nuevo Laredo. (Roughly around 2010, the Zetas split from the Gulf cartel in a spasm of internecine fighting.)

With his achievements during the Nuevo Laredo turf war, Treviño Morales had ensured his path to the top of the Zetas. The battle nearly a decade ago — which saw hit squads target opponents, attacks on the police, and kidnappings — was emblematic of the sort of violence that had come to define Mexico’s drug conflict.

“At the heart of the Nuevo Laredo battle was Mexico’s most bloodthirsty gang, the Zetas,” Grillo writes. “The former special-force soldiers militarized the conflict, turning it from a ‘war on drugs’ to a ‘drug war.'”