Nemesio “El Mencho” Oseguera Cervantes was a feared Mexican drug lord and ruthless cartel leader accused of masterminding a plot to push fentanyl into the United States.
Oseguera, a former police officer, has since become one of the world’s most wanted fugitives, with the United States alone offering a $15 million reward for information leading to his arrest.
Mr. Oseguera, who founded and led the Jalisco New Generation Cartel (CJNG), was an elusive figure who had been considered Mexico’s most powerful cartel boss since the arrest of Sinaloa kingpin Joaquín “El Chapo” Guzmán a decade ago.
According to the U.S. Drug Enforcement Administration (DEA), Oseguera was born in July 1966 in the western state of Michoacán, later immigrated to the United States, and was deeply involved in drug trafficking starting in the 1990s. In 1994, he was convicted of conspiracy to distribute heroin in California and served three years in a U.S. prison.
After returning to Mexico, he worked as a police officer in the western state of Jalisco, but quickly resumed his criminal activities, building influence in the drug underworld and rising to become the head of one of the country’s most powerful and ruthless criminal empires.
Wanted by Mexican and U.S. authorities, Oseguera, or “El Mencho,” kept a low profile, so only a few photos remain of him.
His death Sunday in a Mexican military operation in Tapalpa, in the west coast state of Jalisco, sparked widespread unrest in various parts of the country.
Oseguera had a long career in the field of brutality before forming CJNG. He was at one time the Milenio cartel’s hitman, or chief enforcer, and later oversaw security and violence operations for the famous Sinaloa cartel. Its former leader, Guzman, is serving a life sentence in a US prison.
According to the DEA, the CJNG emerged from the remnants of the Milenio cartel in the 2010s, but the cartel split in a power vacuum after leader Oscar Nava Valencia was arrested in 2009.
According to the DEA, Oseguera founded the group with Abigail González Valencia, the leader of Los Quinis, a family-based cartel operating in Michoacán state. The organization served as CJNG’s financial and logistics arm and oversaw its “diverse network of money laundering activities.”
However, it was only through his marriage to Abigael’s sister, Rosalinda González Valencia, that Oseguera gained real influence in the new organization.
“El Mencho actually reached the cartel’s leadership through a diplomatic strategy through marriage,” public security analyst David Saucedo told CNN in Spanish. “While he was certainly the head of the hit squad for ‘Nacho’ Coronel (leader of the Sinaloa cartel), he lacked the pedigree that his wife Rosalinda had,” Saucedo added.
The fast-growing cartel quickly expanded its influence, asserting a significant presence throughout Mexico and becoming a major player in the global drug trade.
The U.S. State Department said it was a brutal campaign of violence that included assassination attempts on Mexican government officials and murders against rival human trafficking groups and Mexican law enforcement officers.
The cartel demonstrated its firepower in May 2015 when it responded to security operations by simultaneously holding roadblocks in multiple municipalities and shot down a military helicopter. Three soldiers were killed in the clash.
The following year, the gang allegedly brazenly kidnapped Guzmán’s son from a fancy restaurant in Puerto Vallarta. He was released a week later.
It didn’t take long for the DEA to add El Mencho to its most wanted list.
According to U.S. authorities, CJNG has ties to chemical precursor suppliers in China, is deeply involved in the production and trafficking of methamphetamine and fentanyl, and controls multiple ports for importing the chemicals.
According to the DEA, the cartel is a “major supplier of illicit fentanyl” to the United States, generating “billions of dollars in profits,” as well as being one of the major suppliers of cocaine.
The group has contacts in more than 40 countries in the Americas, as well as Australia, China and Southeast Asia, according to the U.S. State Department.
Mexico has been under pressure from US President Donald Trump to take further steps to limit the flow of drugs into the US.
The United States designated CJNG as a terrorist organization in February 2025, and Mr. Oseguera has already been indicted multiple times in the United States, including a 2022 charge of conspiracy to manufacture and distribute methamphetamine, cocaine, and fentanyl for import into the United States.
The death of “El Mencho” on Sunday caused confusion across the country. But that doesn’t necessarily cripple JNGC’s multibillion-dollar drug trade.
The DEA says the gang is structured like a franchise business and consists of about 90 organizations, according to Eduardo Guerrero, director of Mexican consulting group Lantia Intelligence.
“This fragmentation means we will need more complex and sophisticated strategies to weaken and dismantle them,” Guerrero told CNN earlier this year.
Mexico’s military and police, supported by U.S. intelligence and equipment, have previously attempted to eliminate the kingpin. But others emerged to replace them, and large quantities of drugs continued to flow across the U.S. border.
