( CNN ) -- Mexican authorities have captured a suspected leader of the Gulf cartel , officials said Tuesday . A man who `` is presumed to be and says he is '' Mario Cardenas Guillen was detained Monday in the northern state of Tamaulipas , a spokesman for Mexico 's navy told reporters . His brother , Osiel Cardenas Guillen , was the cartel 's founder and former leader . A U.S. federal judge sentenced him to 25 years in prison in 2010 after he pleaded guilty to five felony charges , including conspiracy to possess with intent to distribute , conspiracy to launder money and threatening to assault and kill federal agents . Mario Cardenas Guillen , also known as `` M1 '' and `` The Fat One , '' became one of the cartel 's top leaders that year , after another brother was killed in a Mexican military operation , officials said . Authorities had previously accused him of helping to run aspects of the cartel 's operation while he was in a Mexican prison on organized crime charges . From inside prison , authorities said he operated an auto body workshop that outfitted cars with compartments used to transport cocaine and marijuana to the United States . He was released from prison in 2007 . On Tuesday , Vice Adm. Jose Luis Vergara Ibarra , a spokesman for Mexico 's navy , said Mario Cardenas Guillen was connected with a number of pending cocaine trafficking cases . The Gulf cartel is one of Mexico 's major drug-trafficking organizations . It is based in the Mexican city of Matamoros , across the border from Brownsville , Texas . The cartel split into two factions after its former leader , Antonio Cardenas Guillen -- also known as Tony the Storm -- was killed in a military operation in 2010 , Vergara told reporters Tuesday . Authorities announced the arrest of Mario Cardenas Guillen a day after Mexican President Felipe Calderon defended his drug war strategy in his final state of the union speech . More than 47,500 people have been killed in drug-related violence across Mexico since Calderon deployed federal troops to combat cartels shortly after taking office in December 2006 . The Mexican government has not released official statistics since January , and others estimate a much higher death toll . On Monday , Calderon blamed fighting between rival cartels for the violence . `` Federal intervention has not been the problem . It has been part of the solution , '' he said . Calderon , who will leave office when his term ends in December , urged Mexico 's next government to continue the fight against organized crime . Mexico 's Calderon defends drug war in final state of nation address . Alleged senior member of Tijuana drug cartel extradited to U.S. Man gets 25 years for trying to buy military weapons for cartel .
Police say Mario Cardenas Guillen is a leader of the drug cartel . He was killed in a military operation Monday . He is wanted in connection with a number of drug trafficking cases , officials say . His father , Osiel Cardenas Guillen , was the cartel 's founder and former leader .