Mexican Marines said they had detained the son of Mexico's most-wanted drug kingpin, Joaquin "El Chapo" Guzman, boss of the powerful Sinaloa cartel.
Jesus Alfredo Guzman Salazar, 26, was arrested in an upscale suburb of the western city of Guadalajara, with help from US authorities, the Associated Press cited Navy spokesman Jose Luis Vergara as saying at a news conference.
A US Drug Enforcement Agency official was reportedly present during the arrest.
Marines said they caught Guzman Salazar in a house with a cache of rifles, pistols, grenades and about $160,000 in cash, Reuters reported.
Guzman Salazar — also known as "El Gordo," or "The Fat One" — was supposedly being groomed for a leadership role in Sinaloa cartel, Mexico's most powerful.
"He controlled most of the Sinaloa cartel's illegal drug trade between Mexico and the United States," Vergara said, the BBC reported.
He also served as the administrator of his father's fortune, estimated by Forbes magazine at about $1 billion.
And, The New York Times reported, he coordinated most of the cartel's cocaine and marijuana shipments to the US.
The Sinaloa cartel also controls much of the flow of methamphetamine to the US.
The Treasury Department had placed Guzman Salazar and his mother, María Alejandrina Salazar Hernandez, on a financial sanctions list to block money laundering and any American businesses or citizens from doing business with them, the Times wrote.
A 2009 indictment on drug-related charges in a federal court in Illinois means he can be extradited to the US.
The BBC linked the arrest to the July 1 presidential elections, and Mexican President Felipe Calderon's war on drugs being under scrutiny.
More than 55,000 people have died in drug-related violence since he declared war on the cartels, the BBC wrote.
Guzman himself, jailed in 1993, has been in hiding since escaping from his maximum-security prison in a laundry basket in 2001.
The US state department has offered a $5 million reward for information leading to his arrest.
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