On Monday, Mexican marines captured Miguel Angel Trevino Morales, one of the country's most notorious suspected drug kingpins, in the border city of Nuevo Laredo. Trevino had terrorized the area for years as the leader of a feared cartel, Los Zetas, that has been blamed for a campaign of torture and murder, both in Mexico and across the border in the U.S.

Trevino, known as El 40 or Z-40, reportedly had boasted to associates that he would never be taken alive, but Mexican authorities said he gave up without a fight. "He had a reputation of leading the most vicious group in Mexico," said one law enforcement official. "This is a huge symbolic way to end his career."

The U.S. had offered a $5 million reward for information leading to Trevino's capture, and American drug enforcement officials congratulated their counterparts in Mexico for putting an end to his "ruthless leadership." College of William and Mary professor George Grayson, who has written a book on the Zetas, said that the arrest of Trevino could signal the beginning of the end of the bloody reign of the Zetas, which started off as the violent enforcement wing of another group before breaking away and forming an independent cartel in 2010.

The arrest was the first major blow against a drug cartel for the administration of President Enrique Pena Nieto, who took office in December. The previous administration, led by President Felipe Calderon, captured or killed seven high-ranking cartel leaders beginning in 2011, part of an aggressive, nationwide war on drugs that led to an uptick in violence and a proliferation of gangs as crimes syndicates splintered.

Many of Trevino's top lieutenants went down before he did. Alejandro Hope, a former member of Mexico's intelligence service, told The Associated Press that the arrest is "another link in the destruction of the Zetas as a coherent, identifiable organization."

That doesn't mean the war against Los Zetas is over. Trevino's younger brother, Omar, is expected to take his place. "You're going to have Omar, who's equally as ruthless, although not as highly intelligent as Miguel, but he will be the heir apparent," Mike Vigil, former chief of international operations for the Drug Enforcement Administration, told the Houston Chronicle.

Other powerful cartels also are expected to fight for any turf Los Zetas lose, including the "Sinaloa Cartel, considered the largest and most powerful supplier of cocaine to the United States," according to The New York Times.

There is no denying this is a win for Pena Nieto's government, though. His PRI party has a reputation for "making deals with Mexico's underworld," said Nick Miroff at The Washington Post, and American officials were worried he wouldn't be as determined to fight the drug lords as his predecessor — especially after he slapped new limits on the operations of the CIA and DEA in Mexico.

Now, according to Miroff, Pena Nieto and members of his administration can deliver on a key campaign promise by claiming "they are making progress on two fronts: dismantling cartels and 'reducing violence.'"