The leader of the Gulf cartel was transferred Sunday to Mexico City for questioning after his capture near the northern border with the United States.
Mario Armando Ramirez Trevino was arrested Saturday morning in a military operation near the border city of Reynosa, in the second major blow in a little more than a month to the crime syndicates that have terrorized Mexico for years.
A spokesman for the federal prosecutor's office said that during the night the military turned Ramirez Trevino over for questioning by organized crime investigators.
His capture followed the July 15 arrest of Miguel Angel Trevino Morales, the head of the paramilitary Zetas cartel.
President Enrique Pena Nieto, who took office in December 2012, has pledged to reduce the drug-related violence that has resulted in more than 70,000 deaths since 2006.
Ramirez Trevino, thought to be 51, became head of the once-powerful Gulf cartel after its former leader, Jorge Eduardo "El Coss" Costilla, was arrested in September 2012.
The Gulf cartel first emerged as a liquor smuggling ring during the Prohibition era in the 1930s and is one of Mexico's oldest criminal groups.
Even though it has lost considerable terrain to rivals since its heyday in the mid 2000s, it retains key smuggling routes in eastern and northeastern Mexico.
Ramirez Trevino was captured in Rio Bravo, near the Texas border, according to a justice source in the northeastern state of Tamaulipas.
The United States had offered a $5 million reward for information leading to the arrest of Ramirez Trevino, who was indicted in a US federal court in 2008 on crimes related to trafficking cocaine and marijuana from Mexico into the United States.
The interior ministry said it would hold a press conference on Sunday to discuss the details of his arrest.
Military checkpoints were set up outside Rio Bravo and the nearby border town of Reynosa, while soldiers and marines patrolled the streets, local media reported.
Soldiers also took control of the international airport at Reynosa, and Mexican military helicopters buzzed across the region on Saturday.
Reportedly a former drug addict, Ramirez Trevino -- also known as "El Pelon" ("Baldy") and "X-20" -- rose to lead the Gulf cartel unit that controlled criminal activities in the key smuggling town of Reynosa, across the Rio Grande river from McAllen, Texas.
In recent months he reportedly asserted his leadership over the cartel by crushing a rival faction.
Ramirez Trevino earlier worked closely with Osiel Cardenas Guillen, a former powerful cartel leader arrested in 2003 and currently serving a lengthy prison sentence in the United States.
Under Osiel Cardenas the Gulf cartel hired the Zetas -- elite anti-drug commandos who deserted -- to work as their enforcement arm. But the Zetas turned on their employers in 2010 and in a series of bloody turf battles took over most of their territory.
The Zetas now battle the western Sinaloa Federation for control of the major drug trafficking routes to the United States. The Sinaloa gang is headed by Joaquin "El Chapo" (Shorty) Guzman, Mexico's most wanted man.
The captured former head of the Zetas, alias "Z-40," is currently being held in a maximum security prison in Mexico.
The two high-profile successes in Mexico help balance out some major setbacks, including the surprise release of jailed drug lord Rafael Caro Quintero, convicted in the 1985 torture and killing of US Drug Enforcement Administration agent Enrique Camarena and his Mexican pilot.
A local judge in the state of Jalisco on August 7 ordered Caro Quintero's release, claiming procedural mistakes in his case. The Mexican government has since ordered his detention again after receiving a US extradition request.
Mexicans have become so outraged by the cartels' violence and distrustful of authorities that in some areas residents have taken up arms and formed self-defense groups.
The bodies of 24 people were found last week in two states where vigilantes have been especially active, local officials said Saturday.
The remains of nine men with their hands tied and apparently tortured to death were found in a remote region of the western state of Michoacan, local officials told AFP.
In the nearby state of Guerrero eight people were killed in a battle with self-defense groups, state police said, while another seven bodies were found late Friday in Taxco, also in Guerrero.
A shadowy pseudo-religious regional cartel, the Knights Templar, are active in the area.