Mexico City, Oct 9 (IANS/EFE): The man in charge of northeast Mexico for the Los Zetas drug cartel was captured by marines and faces charges of ordering the killings of more than 300 people, including 72 migrants massacred in 2010, officials said Monday.

Salvador Alfonso Martinez was allegedly in charge of the cartel's operations in the states of Tamaulipas, Nuevo Leon and Coahuila.

Martinez was arrested Saturday in Nuevo Laredo, which is across the Rio Grande from Laredo, Texas.

The drug trafficker was detained as he drove through the border city's El Campanario district a few hours after a shootout between marines and Zetas gunmen in Nuevo Laredo, which is in Tamaulipas, navy spokesman Rear Adm. Jose Luis Vergara said.

Authorities were offering a reward of up to $1.2 million for information leading to the arrest of the 31-year-old Martinez, who was a "trusted man and direct associate of Miguel Angel Trevino Morales", considered the top Los Zetas boss, Vergara said.

Martinez, who smiled and appeared defiant during Monday's press conference at the Attorney General's Office, is considered the "intellectual author of the deaths of 72 undocumented migrants" at a ranch outside the city of San Fernando, Tamaulipas, in August 2010, Vergara said.

He is suspected of being behind the killings of more than 200 people whose bodies were found in clandestine graves in Tamaulipas, as well as the murders of 50 other people in different parts of Mexico.

David Hartley, a US citizen murdered Sep 30, 2010, and police Maj. Rolando Armando Flores Villegas, who was investigating the American's killing, were among Martinez's victims.

"It is presumed that he is also linked to the escape of 151 inmates from the prison in Nuevo Laredo, Tamaulipas, that occurred in December of 2010," as well as the escape of 132 inmates Sep 17 from the prison in Piedras Negras, Coahuila, Vergara said.

Martinez began his criminal career in Nuevo Laredo, his birthplace, in 2002, when he was recruited by the Gulf cartel, which employed Los Zetas as its armed wing, to be a lookout.

He became a hitman in 2004, taking his orders from Trevino Morales and becoming the No. 2 man in Nuevo Laredo two years later.

Martinez was sent in 2008 to be the cartel's boss in Coatzacoalcos, a city in the eastern state of Veracruz, where he was arrested and later freed from jail by a group of gunmen.

After spending a few months in hiding in Coahuila, Martinez was sent to fight for turf in the northern states of Durango and Chihuahua until 2010, when Los Zetas broke with the Gulf cartel and he became the boss in Tamaulipas.

Five other cartel members were arrested in two separate operations following the capture of Martinez, the navy said.

Marines seized five rifles, two handguns, two grenades, more than 2,000 rounds of ammunition, two vehicles and other gear from the suspects.

Heriberto Lazcano Lazcano, known as "El Lazca", deserted from the Mexican army in 1999 and formed Los Zetas with three other soldiers, all members of an elite special operations unit, becoming the armed wing of the Gulf drug cartel.