The head of Mexico's largest drug cartel, Los Zetas, is believed to have been killed in a gun battle with the Mexican Navy, authorities said Monday.
Strong evidence points to Heriberto Lazcano Lazcano as one of two men killed in a shootout Sunday in the northern state of Coahuila, according to a Navy news release.
But, the navy added, it will need to carry out more forensic tests to make a final determination.
The Los Zetas cartel -- headquartered in Nuevo Laredo, directly across the border from Laredo, Texas -- is Mexico's largest drug cartel in terms of territory and has operations in 11 Mexican states.
The cartel sends thousands of kilograms of cocaine and other drugs annually to the United States, generating many millions of dollars.
Lazcano, who is the subject of a $5 million reward from the U.S. State Department and another $2.3 from Mexican authorities, has been rumored killed or captured several times in the past.
If indeed Lazcano is dead this time, it will be a blow to the cartel, but would not necessarily mean its demise. The Zetas is not centralized as some other cartels, such as La Familia, analysts say.
Lazcano, 37, joined the Mexican armed forces in 1991 and served as part of its elite Airborne Special Forces Group, dedicated to battling drug cartels.
Soon after, Lazcano and several other Special Forces members were recruited by the Gulf cartel to create its enforcement arm, Los Zetas.
In the ensuing years, the Zetas split into its own major drug trafficking organization, and have since branched out into extortion, kidnappings, and human smuggling.
The Zetas is in the midst of a bloody turf war with its former employer, the Gulf cartel, and also with the Sinaloa cartel. The fight, for access to lucrative smuggling routes in northern and central Mexico, has left thousands of civilians dead.
The violence is particularly acute in three northeastern states that are some of the Zetas' strongest-held territory: Coahuila, Nuevo Leon and Tamaulipas
In May, authorities found 49 decapitated and dismembered bodies along a highway in Nuevo Leon. The orders to commit the grizzly crime allegedly came from Lazcano himself, who originally wanted the bodies to be left in a town's central square.
"100 percent Zeta" was painted in black graffiti on a wall at the entrance of a nearby town, indicating Mexico's paramilitary-trained cartel had committed another atrocity on a stunningly large scale.
But days after the bodies turned up, new banners turned up hanging in locations throughout the country, purportedly from the Zetas, claiming that the notoriously ruthless cartel had nothing to do with the gruesome crime.
Last year, the bodies of 72 migrants from Central and South America were discovered at a ranch in Tamaulipas state.
The Zetas have been blamed for the mass graves and for the deaths of the migrants.
The shootout Sunday occurred when Mexican Navy vehicles on patrol were attacked by assailants from a moving vehicle using grenades and firearms. One naval service member received non-life threatening injuries in the engagement, the Navy said.
Two attackers were killed. And authorities are hoping that Lazcano, who earned the nickname "The Executioner," is one of them.