Security forces have unearthed six more bodies in a northeastern Mexican border state where a drug gang is believed to be kidnapping passengers from buses and hiding their victims in secret graves, authorities said Tuesday.
A total of 183 bodies have been discovered in a month in 40 graves.
The horrific discoveries have intensified criticism that lawlessness reigns in Tamaulipas state, where the Zetas drug gang has terrorized migrants trying to make their way north to the United States. It is the same region where authorities say the Zetas killed 72 Central American migrants in August.
Meanwhile, a different search over the last month in the capital of northwestern Durango state has yielded 96 bodies in two mass graves as of Tuesday, said Gerardo Ortiz, spokesman for the state attorney general's office.
State investigators led by federal agents have exhumed 79 bodies in a car repair shop of a working-class neighborhood of Durango city, Ortiz said. Seventeen other decomposed bodies were found in mid-April next to a well-known hacienda in the city, less than a mile away from the car shop.
Ortiz said the bodies appear to have been buried under dirt for anywhere from six months to six years, but authorities don't know for sure because they haven't done tests.
He wouldn't say who the victims likely were or the motives. But unlike in Tamaulipas, where states across Mexico sent reports of missing persons and families lined at up morgues to give DNA samples, no one has been calling Durango. Very few families have inquired about loved ones, Ortiz said.
He said perhaps families were afraid to come forward, but he didn't want to speculate.
Both excavations are part of an investigation by the federal Attorney General's Office, Ortiz said.
But an official in the federal office disputed that. The official, who insisted on not being quoted by name, said state authorities are in charge of the Durango invesigation.
Federal Attorney General Marisela Morales said at a news conference Tuesday that six more bodies had been discovered in the San Fernando area of Tamaulipas just south of the U.S. border in the past week.
Security forces began exhuming the corpses on April 1 after they were led to the site by suspects who confessed to kidnapping and killing bus passengers traveling through the area.
The motive for the bus abductions remains unclear, though prosecutors have suggested the gang may be forcefully recruiting people to work for it. Morales said the Zetas have also been extorting migrants for up to $2,000. Those whose families pay are led across the border to the U.S. by the Zetas themselves, she said.
The discoveries of the mass graves have sparked sporadic protests by citizens.
Alejandro Poire, the government spokesman for security issues, insisted "the government is in control of Tamaulipas."
He said the government has sent more federal police to the state and is aggressively investigating the mass killings and working to prevent more deaths.
He said the increased federal presence has led to the rescue of 119 kidnapped people in the northern Tamaulipas city of Reynosa in recent days, including Mexican, Central American and Chinese migrants.
Morales said 74 suspects have been arrested in the Tamaulipas killings, including 17 officers in San Fernando's municipal police force who were identified as collaborators of criminals by some of the detainees.
Only two of the 183 victims have been identified, Morales said. Mexican authorities have declined to reveal their identities, but the Guatemalan government has said one was a Guatemalan national.
A number of mass graves have been discovered over the past in areas of Mexico where drug gang turf wars have been the fiercest.
President Felipe Calderon stepped up the fight against drug traffickers when he took office four years ago, deploying thousands of federal police and soldiers to cartel strongholds.