MEXICO CITY – The Los Zetas cartel’s boss in Nuevo Laredo, a city in the northeastern Mexican state of Tamaulipas, died in a shootout with military personnel last week, the armed forces said.

Gerardo Guerra Valdez was killed last Thursday, the armed forces said.

Another Zetas cartel boss was among 13 gunmen who died in the shootout in Quila.

Guerra Valdez escaped from prison in June 2009, “causing the deaths of three inmates and a person visiting” the penitentiary, the armed forces said.

“He had been the Los Zetas boss in Nuevo Laredo since Aug. 2, 2011, following the death of Jorge Luis de la Peña Brisuelas, alias ‘Pompin,’” the armed forces said.

Nuevo Laredo, located across the Rio Grande from Laredo, Texas, has been a Los Zetas stronghold in the turf war against the rival Gulf cartel.

“Guerra participated actively in the violent acts that his criminal organization committed along the border” and was “one of the (gunmen) closest to and most trusted” by boss Miguel Angel Trevillo Morales, the armed forces said.

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.

After several years on the payroll of the Gulf cartel, Los Zetas, considered Mexico’s most violent criminal organization, went into the drug business on their own account and now control several lucrative territories.

Mexico’s drug war death toll stood at 47,515 from December 2006 to Sept. 30.

The murder total has grown every year of President Felipe Calderon’s military offensive against the well-funded, heavily armed drug cartels.

Unofficial tallies published in December by independent daily La Jornada put the death toll from Mexico’s drug war at more than 50,000. EFE