CADEREYTA, Mexico -- Authorities struggled Monday to identify 49 bodies without heads, hands or feet to gain clues into the latest in a series of massacres from an escalating war between Mexico's two dominant drug cartels, with increasing evidence that innocents are being pulled into the bloodbath along with gang rivals.
More than 24 hours after the gruesome discovery, officials had yet to identify any of the mutilated corpses found near the northern industrial city of Monterrey. None of the bodies examined so far showed signs of gunshots, Nuevo Leon state security spokesman Jorge Domene told Milenio television.
Though it was unclear who the victims were, it was the fourth massacre in a month. Mexico's interior secretary, Alejandro Poire, said Monday that all those incidents resulted from the fight between the Zetas gang and the Sinaloa Cartel, which have emerged in the last year as the two main forces in Mexican drug-trafficking and other organized crime.
Some victims in earlier body dumps have turned out to be bakers, brick layers, even students -- anyone who could be snatched off the streets in mass killings that one captured gang member said were designed to "cause terror."
Mr. Poire would not respond directly when asked if innocents have increasingly become targets.
"We don't have proper identification of the dead," he said. "We have to leave that to the investigation."
"We have to look deeper ... to know the motives or who could have been the victims of violence," Mr. Poire added.
The 43 men and six women found Sunday were dumped at the entrance to the town of San Juan in the municipality of Cadereyta about 105 miles southwest of McAllen, Texas.
Graffiti around the town of 4,000 people mark it as Zetas territory, including "100% Zeta" painted on a stone arch welcoming visitors where the bodies were dumped and "Z's" painted on the home of San Juan's priest.
There have been 74 killings in the first four months of this year in Cadereyta municipality, compared with 27 over the same period in 2011 and seven in 2010, according to figures from Nuevo Leon state prosecutors.
The massacre follows the discovery of 14 men left in a van in downtown Nuevo Laredo on April 17 and 23 people found hanged or decapitated in the same border city May 4.
Eighteen dismembered bodied were left near Mexico's second-largest city, Guadalajara, last week. Among the nine people identified in that attack were bricklayers, waiters and at least one student. None had criminal records.
Accused Zetas member Juan Carlos Antonio Mercado was arrested near Guadalajara last week in the kidnapping of 12 people. He told reporters that he and accomplices had been kidnapping people since mid-April at random and held them with the intent of dumping their bodies in the city center on May 10, Mexican Mother's Day, but the police presence kept them from doing so.
Prosecutors in Jalisco state, where Guadalajara is located, said the kidnapping plot fell apart when some victims escaped. The plot appeared to be linked to the discovery of the 18 dismembered bodies.
Drug violence has killed more than 47,500 people since President Felipe Calderon launched a stepped-up offensive when he took office in December 2006. The campaign has seen the two cartels emerge as Mexico's two most powerful. At least one of the two cartels is present in nearly all of Mexico's 32 states.
Their war started in earnest last fall with the dumping of 35 bodies in Veracruz, a strategic smuggling state with a giant Gulf port formerly controlled by the Zetas and recently taken over by a gang loyal to Sinaloa.