Heriberto 'The Executioner' Lazcano, head of the the Zetas drug gang (Reuters)

Mexican authorities have killed one of the country's most wanted drug lords, Los Zetas' chief Heriberto Lazcano, aka El Lazaca or The Executioner.

El Lazaca was reportedly shot dead in an exchange of fire with the Mexican Navy marines - regarded as incorruptible - in the northern state of Coahulia.

It took two days for forensics to confirm that one of the two gang members gunned down in a car 125km (80 miles) west of the Texan border, was the powerful and bloodthirsty boss of Los Zetas.

Marines opened fire as El Lazaca sped off in his car, hurling hand grenades at his pursuers.

His death is one of the greatest coups for the Mexican authorities since President Felipe Calderon launched a war on drug cartels in 2006. He had been erroneously reported dead after a shootout in 2007.

Los Zetas are considered the second most powerful drug gang in Mexico and Lazcano was directly involved in hundreds of murders, mass killings and kidnappings.

The US government had put up a $5m (£3.1m) reward on his head, to which Mexico added $2.3m.

Lazcano, 38 enlisted in the army at the age of 18 and quickly became a member of the country's elite Special Forces.

Six years later he deserted the army with fellow special corps members and went into drug trafficking, offering his military expertise to the Gulf Cartel.

In 2010, his group of army deserters broke away from the cartel and formed the Zetas, sparking a bloody turf war.

With more than 10,000 gunmen to call on, the gang shortly became one of the biggest players in drug trafficking in Mexico.

It was recently accused of killing the son of Mexican politician and former Coahuila governor Humberto Moreira. It is believed the murder was ordered in retaliation for a crackdown on organised crime.

Lazcano is the last of a series of important victories against drug lords attributed to the Mexican Navy. Gulf Cartel bosses Mario Cardenas Guillen (alias El Gordo) and Jorge Costilla (El Coss) were arrested in September.

According to analysts, the Navy is the least corrupted of all Mexico's armed forces and has the closest ties with the FBI.

About 60,000 people have died in the war on drugs in Mexico in six years.

Mexico navy
Mexican marines have conducted the majority of anti-drug recent operations (Reuters)