The body of the leader of a Mexican drug cartel, who was killed in a shootout with marines, has been stolen by an armed gang, state officials say. The corpse of Heriberto Lazcano, founder of the brutal Los Zetas gang, was being stored by the authorities at a funeral parlour in northern Mexico. The Mexican navy said tests confirmed that the man killed was Lazcano. Infamous for mass killings, the Zetas control key drug-trafficking routes in north-eastern Mexico. Lazcano, also known as "the executioner", was killed in a gun battle with marines on Sunday in Progreso, some 125km (80 miles) west of the Texan border in Coahuila state, the navy said. It added that fingerprints and photographs of the body were taken before it was handed over to the local authorities in Coahuila. Early on Monday, a group of armed men raided the funeral parlour where the corpse was being kept, and stole it, attorney general Homero Ramos told a news conference on Tuesday. His statement came shortly after the navy confirmed the identity of the body as Lazcano's, saying the fingerprints matched those on its database. The photographs of the body were also made public. Gang split Lazcano is suspected of involvement in hundreds of killings, including that of crusading newspaper editor Francisco Ortiz Franco in 2004. The US had put up a $5m (£3.1m) reward and Mexico another $2.3m for information leading to Lazcano's capture. Mexican police believe a recent surge in mass killings is due to a split within the Zetas cartel. Lazcano was thought to be the leader of one faction, while the other is led by Miguel Angel Trevino Morales. In the nearly six years of Felipe Calderon's presidency, more than 50,000 people are believed to have died in violence blamed on organised crime. The navy has been at the forefront of operations against Mexico's drug cartels. On Monday, it said it had arrested suspected regional Zetas leader Salvador Alfonso Martinez Escobedo, who the navy says was behind the 2010 murder of 72 migrants in northern Tamaulipas state. Officials say Escobedo works for Trevino Morales. Morales, known as Z40, has a reputation for equal if not greater brutality than Lazcano and remains at large.