The Mexican navy is reporting that top Zetas drug cartel leader Heriberto Lazcano has been killed in a firefight with marines in the northern border state of Coahuila.

According to a statement by the navy, obtained by the Associated Press, there was strong evidence the body of one of two men killed in the shootout Sunday was Lazcano, known as "El Lazca." While no source has confirmed the body in question to be that of Lazcano, officials are planning forensics tests to confirm the identification.

"Information was obtained after the first forensics tests were carried out that yielded indications that suggest that one of the bodies is Heriberto Lazcano," the navy's statement said.

Lazcano is said to be a founder of the Zetas cartel, along with other deserters from an elite army unit. Together, the cartel carried out some of Mexico's bloodiest massacres, biggest jail breaks and fiercest attacks on authorities. The death of a top member such as El Lazca" would be a major blow to the cartels hierarchy.

Lazcano, who is also known as "El Verdugo” (the Executioner) for his brutality, is suspected in hundreds of killings, including the June 2004 slaying of Francisco Ortiz Franco, a top editor of a crusading weekly newspaper in Tijuana that often reported on drug trafficking. Ortiz Franco was gunned down in front of his two young children as he left a clinic.

The United States has offered a $5 million reward and Mexico an additional $2.3 million for information leading to Lazcano's arrest, according to the Associated Press.

The Sunday shootout which reportedly claimed the life of Lazcano took place in the rural area of Progreso, Coahuila, about 80 miles west of the Texas border, near Laredo.

In the events leading up to the shootout, the Navy said it received complaints about armed men in the area and sent out a patrol to check out the reports. Gunmen then tossed grenades at the patrol from a moving vehicle, wounding one of the marines. His injuries were not life-threatening.

Two of the gunmen were killed in the ensuing shootout, the navy's statement said. In the gunmen's' vehicle, authorities found a grenade launcher, 12 grenades, what appeared to be rocket propelled grenade launcher and two rifles.

On Saturday, Salvador Alfonso Martinez Escobedo was arrested Saturday in Nuevo Laredo, across from Laredo, Texas. A Navy spokesperson tells AP that Martinez is believed to have masterminded the massacre of 72 migrants in the northern state of Tamaulipas in 2010.

Known to his associates as "Squirrel," Escobedo also has been linked to the escape of 151 prisoners in 2010 from a jail in the city of Nuevo Laredo, the recent flight of 131 prisoners in the city of Piedras Negras and the killing of U.S. citizen David Hartley in 2010 on Falcon Lake, which straddles the U.S.-Mexico border.

The navy is also blaming Martinez for the killing of the Tamaulipas state police commander and chief investigator on the case, an attack that hampered the investigation.

The navy said Martinez is also a suspect in dozens of killings of people who were buried in mass graves at the same site of the 2010 massacre of migrants. Nearly 200 bodies were discovered in April 2011 in the town of San Fernando, close to the U.S. border. Those two crimes have been the most fatalities since Mexico's federal government launched an armed offensive against drug traffickers in December 2006.