( CNN ) -- The alleged leader of a firearms trafficking network believed to be smuggling guns into Mexico -- where police say they are used against law enforcement officers by members of Mexican drug cartels -- was arrested Thursday in Arizona , authorities said . Victor Varela was arrested by the ATF as part of the agency 's ongoing Project Gunrunner . Victor Varela was arrested by the U.S. Bureau of Alcohol , Tobacco , Firearms and Explosives as part of the agency 's ongoing Project Gunrunner , according to an ATF release . He was in the custody of the Maricopa County , Arizona , sheriff . `` Law enforcement officers disrupted a group of gun traffickers and recovered several weapons , including .50-caliber semiautomatic rifles and several handguns , allegedly intended to supply drug traffic organization members of the Juarez Cartel in Palomas , Mexico , '' the statement said . In state charges , prosecutors allege Varela and his co-defendants bought a number of guns in Arizona intending to supply the Mexican cartel members . The group allegedly transported the illegally purchased guns to New Mexico , and then into Mexico . A .50-caliber weapon is the largest that can legally be bought in the United States , and is illegal in Mexico . Authorities believe a .50-caliber weapon was used in recent months to kill Francisco Ledesma Salazar , a police commander in Juarez , Mexico . He is among five high-ranking Mexican police officials killed this year in what Mexico authorities describe as an escalating war between police and drug cartels . Last week , 2,000 troops were sent to Juarez by the Mexican government in an effort to quell the violence there , which has claimed some 200 lives since January . Guns are difficult to buy legally in Mexico , but can be obtained just north of the border at gun shows and gun shops . Project Gunrunner was launched as an effort to help Mexican police by cracking down on illegal smuggling of guns and ammunition , and has led to several arrests and seizures . Watch how the weapons fuel a little-known war » . `` This case was made one of our highest priorities because of the nature of the crime alleged to be committed by Varela , '' U.S . Marshal David Gonzales said in the ATF release . Guns featured in a CNN Special Investigations Unit report last week , confiscated by Juarez police , are believed to have been smuggled into Mexico by Varela , according to an ATF spokesman . Authorities said one recent discovery , in a storage locker in Yuma , Arizona , yielded 42 weapons and hundreds of rounds of .50-caliber bullets already belted to be fed into a machine gun-style weapon , as well as Fabrique Nationale pistols , semiautomatic handguns that fire a 5.7-by-28-millimeter round . `` What 's interesting about this gun , why it 's in high demand , is the nickname that it has in Mexico , '' said William Newell , ATF special agent in charge , about the Fabrique National pistol . `` It 's called 'mata policias , ' or 'cop killer . ' `` Charging documents allege that Varela was attempting to buy a fully automatic M-60 machine gun for a drug cartel associate in Palomas , authorities said . `` Additionally , a number of firearms recovered by Mexico law enforcement ... allegedly were trafficked by Varela 's gun smuggling network , '' the ATF statement said . U.S. authorities are sharing intelligence with their Mexican counterparts to assist in ongoing investigations , the ATF said . E-mail to a friend . CNN 's John Murgatroyd and Drew Griffin contributed to this report .
Suspect is alleged leader network believed to be smuggling guns into U.S. . Last week , 42 Mexican troops were sent to the U.S. Bureau of Alcohol , Tobacco , Firearms and , Mexico , to quell violence . Mexican drug cartels blamed for killings of police officers . ATF : Mexico authorities sharing intelligence with their Mexican counterparts .