Authorities in the central state of Mexico arrested a suspected drug-gang leader who confessed to directly carrying out 300 homicides and ordering 600 others.

Oscar Osvaldo Garcia Montoya, a deserter from Mexico's marines, is one of the country's deadliest drug assassins, Mexico state Attorney General Alfredo Castillo said at a press conference.

The arrest was made Thursday at a home in the Mexico City borough of Tlalpan that was being used as a safe house for Garcia Montoya's La Mano con Ojos (The Hand with Eyes) gang, he said.

Agents from the federal Attorney General's Office, the Mexico City District Attorney's Office and the Mexico state AG's office participated in the operation.

Garcia Montoya, originally from the northwestern Mexican town of Guasave, also went by the name of Jesus Castro Serrano.

The federal AG's office had been offering 5 million pesos (more than $400,000) for information leading to the suspect's capture, although authorities did not know his real name and had only identified him by one of several aliases.

Among other crimes, authorities say Garcia Montoya was behind the massacre of 24 people in the La Marquesa forest outside Mexico City in September 2009.

He also is suspected of controlling drug distribution in several towns in Mexico state, which surrounds Mexico City, as well as in part of the Mexican capital.

Authorities in Mexico state blame La Mano con Ojos for the killings of 18 men and two women since November 2010.

The suspect received military instruction from the Mexican marines before deserting and also was trained in Guatemala by an elite special operations force known as the Kaibiles, which he said taught him "how to kill," Castillo said.

Garcia Montoya also worked as a police officer in Baja California Sur state and as a municipal police in the cities of Los Mochis and Ahome in Sinaloa state, where he entered the drug business in 2002 as a member of the Beltran Leyva organization, first as a hit man and later as a bodyguard for the group's top leaders.

He later split from the Beltran Leyva gang and founded La Mano con Ojos, which is known for using extreme violence against its rivals, Castillo said, adding that the organization was notorious for decapitating the majority of its victims.

The suspect said after his capture that this weekend he was going to decapitate "six members of his organization who wanted to desert" and planned to record some of the killings and send the videos to the media.

The state attorney general said he will request that Garcia Montoya be held at a maximum-security facility.

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