The FBI and Spanish police forces blocked a major Mexican drug cartel from launching a European operation. Sinaloa cartel member Jesus Gutierrez Guzman was part of the operation. Guzman, is alleged to be the cousin of Joaquin Archivaldo Guzman, known as "El Chapo," the leader of the Sineloa cartel.

The ministry said the cartel wanted to make Spain a gateway for operations in Europe, even carrying out test runs using shipping containers without drugs. But investigators managed to monitor many of the group's activities and intercepted a container carrying 373 kilos (822 pounds) of cocaine in late July before moving in to make the arrests.

The Interior Ministry statement said Jesus Gutierrez Guzman, Rafael Humberto Celaya Valenzuela, Samuel Zazueta Valenzuela and Jesus Gonzalo Palazuelos Soto were arrested near their hotels in the Spanish capital. The statement did not say precisely when the arrests were made, and when called by phone ministry officials could not immediately give exact details of the dates.

Jesus Gutierrez Guzman is alleged to be the cousin of Joaquin Archivaldo Guzman, known as "El Chapo," the leader of the cartel and Mexico's most wanted man. Since escaping prison in 2001, Joaquin Archivaldo Guzman has run the Sinaloa cartel, one of Mexico's two most powerful drug-organizations, from a series of hideouts and safe houses across Mexico.

Law-enforcement officials say he has earned billions of dollars moving tons of cocaine and other drugs north to the United States. In recent months, the Sinaloa cartel and its allies have been waging a brutal war against the paramilitary Zetas cartel across Mexico, often carrying out mass killings that have left hundreds of dismembered bodies dumped in public places.

Along with the alleged link to the cartel leader, the arrests in Spain have attracted a great deal of media interest in Mexico because a Facebook page in Celaya Valenzuela's name appears to show a photograph of him alongside Mexico's President-elect Enrique Pena Nieto. The photo was posted on Feb. 11. The presidential elections were held in July.

The operation against the Sinaloa cartel was made possible thanks to agents using "the most modern research techniques," which had at all times been supervised by judges and prosecutors, the Interior Ministry statement said. It noted that "the bulk" of the investigation was carried out in the United States.

U.S. agents had learned that cartel members were planning to travel to Spain and were later able to confirm the trip, which took place in March 2011, the statement said. Thanks to the information provided by the FBI's Boston division, Spanish police located the suspects and monitored them closely "to ensure their full identification," the statement said.

The statement said FBI investigators had determined that the gang intended to begin large cocaine shipments by sea with the drugs concealed in cargo containers. The cartel used stringent security measures to try to ensure the success of the operation and did several test runs, initially shipping containers without any drugs in them.

When they sent a first drugs shipment to Spain on board a ship from Brazil in late July, officers intercepted it, the statement said.

The arrest of his alleged cousin could potentially lead to information about the whereabouts of the fugitive Mexican drug lord. Investigators working to bust Sinaloa's operations thought in June that they had nabbed a son of Joaquin Archivaldo Guzman, but it turned out they got the wrong man.

Based on reporting by the Associated Press.

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