The leader of a Mexican drug cartel was apprehended by police in Mexico City Thursday. Oscar Garcia Montoya is suspected of ordering the beheading of 600 people in the capital, the heads of whom he allegedly scattered in streets and surrounding towns.

"He has admitted to taking part personally in 300 executions, and ordering another 300," Alfredo Castillo, the prosecutor for the state of Mexico told a news conference.

Garcia -- nicknamed "El Compayito," which is the name of a popular hand-puppet in Mexico -- is assumed to be the leader of the dangerous "Mano con Ojos" or "Hand with Eyes" cartel, which itself is a recent off-shoot of the Beltran Leyva cartel. He likely took over the gang after the former leader, Arturo Beltran, was killed in a shoot-out with Mexican marines in 2009.

According to Castillo, Garcia is a former Navy corporal, and at some point received training from the Kaibiles, an elite Guatemalan commando unit. Four ex-Kaibiles were recently sentenced to a total of 6,000 years in prison for their involvement in the Dos Erres massacre, where almost 250 people were killed during Guatemala's civil war.

Garcia's resume does not stop there. "El Compayito" (the name-sake puppet is literally a hand with eyes) is apparently a former police officer who deserted the force to become a mafia boss' bodyguard.

Drug-related violence in Mexico exploded in 2006 when the government and President Felipe Calderon launched an offensive against organized crime. Since then, more than 40,000 people have been killed, including civilians, government officials and soldiers.

Recently, government forces have made a number of high-profile arrests. Earlier this month, police captured Jose Antonio Acosta Hernandez, known as "El Diego," who is thought to be the leader of the La Linea gang, the enforcement arm of the Juarez cartel in the northern state of Chihuahua.

Acosta, who is also a former policeman, admitted to ordering the murders of 1,500 people. He is also thought to be involved with the death of three people with ties to the U.S. Consulate, including a consulate employee and her husband, in 2010.

In June, police captured Acosta's second-in-command. Marco Antonio Guzman Zuniga, who is nicknamed "El Brad Pitt," was arrested on charges relating to a car bomb detonated outside a police station last year.