Authorities in Mexico say they have arrested one of the country's most wanted drug traffickers, Sergio Villarreal, who is said to work for the Beltran Leyva cartel.Sergio Villarreal known as , 'El Grande,' was arrested by marines along with two other people in the central city of Puebla, east of Mexico city.According to authorities, Villarreal was a key participant in a bloody struggle for the leadership of the Beltran Leyva cartel that began after former chief Arturo Beltran Leyva was killed last year.Villarreal and Hector Beltran Leyva, Arturo's brother, were feuding with would-be cartel leaders including Edgar Valdez, also known as "La Barbie," who was captured by authorities on August 30.More than 28,000 people are believed to have been killed in drug cartel-related violence in Mexico since 2006, when President Felipe Calderon launched a military crackdown.