[2] Authorities investigating the massacre reported numerous hijackings of passenger buses on Mexican Federal Highway 101 in San Fernando, and the kidnapped victims were later killed and buried in 47 clandestine mass graves.

They speculate that the Zetas may have forcibly recruited the passengers as foot soldiers for the organization, intending to hold them for ransom or extort them before they crossed into the US.

[19] In San Fernando, Gulf Cartel forces led by Antonio Cárdenas Guillén "strung the bodies of fallen Zetas and their associates from light poles.

According to The Monitor, the municipality of San Fernando is a "virtual spiderweb" of dirt roads that connect with Monterrey, Nuevo Laredo, Reynosa, and Matamoros—making it a prized territory for drug traffickers.

[20] In August 2010, Mexican Naval Infantry found 72 dead immigrants—58 men and 14 women—in San Fernando, killed by Los Zetas for their failure to pay their ransom and their refusal to work for the cartel.

[21] An Ecuadorian survivor faked his death and made it up to a military checkpoint, and subsequently led authorities to the 72 dead inside a warehouse on a ranch.

[26] This discovery led officials to acknowledge that the Mexican drug cartels had begun to inflict fear through a new modus operandi: "stopping buses and removing passengers, some never to be seen again.

[30] Witnesses then reported that cartel members had stopped the bus at a fake military checkpoint, and that they had ordered the passengers to "pay up to $300 US dollars" for them to continue on their route.

[32][33] It was then proven by the PGR that the massacre was carried out by Los Zetas, a drug trafficking organization formed originally by former military soldiers in Mexico.

[41] Finally, on 7 June 2011, the bodies found in clandestine mass graves in the municipality of San Fernando, Tamaulipas, stopped at 193 corpses.

[43] Houston Chronicle journalist Dane Schiller interviewed an alleged cartel member, who explained Los Zetas had been using an "ancient Roman gladiator blood sport" to groom new assassins and to find recruits for their organization.

A cartel member on trial in Laredo, Texas, testified that the fighting contests between the kidnapped victims were ordered by Miguel Treviño Morales, a high-ranking Zeta lieutenant, and that they were used to make the killers "lose their fear.

"[46] Those who traveled through this highway in 2010 and 2011 used to see "burned vehicles, bullet-shot trucks on the side of the road, and dead bodies, often decapitated, that the cartels would leave behind.

[48] Another survivor stated that heavily armed men would stop buses at roadblocks, and then force women and young girls at gunpoint, "strip them naked, rape them," and then drive away in trucks, leaving the passengers traumatized.

[50] On 17 June 2011, federal police captured Édgar Huerta Montiel, a high-ranking boss in Los Zetas and the man responsible for the killing of 72 migrants in 2010.

[51][52] Isabel Miranda de Wallace of "Stop the Kidnappings" suspects that the mass graves in San Fernando contain more than 500 dead, but that the government of Tamaulipas has not released such information because of the political troubles it may instigate.

[53][54] On 17 April 2011, in the capital city of Ciudad Victoria, Mexican authorities captured Martín Omar Estrada Luna, alias El Kilo, lieutenant boss of Los Zetas in San Fernando, Tamaulipas, and responsible for at least 217 killings in that locality.

"[58] On 17 June 2011 in Fresnillo, Zacatecas, the Federal Police captured Édgar Huerta Montiel, alias El Wache, a high-ranking lieutenant of Los Zetas and the man responsible for the killings of the 72 immigrants.

One Zeta leader accused of involvement was still on the run as of July 2013: Román Ricardo Palomo Rincones, alias El Coyote.

[66] Marisela Morales, the Attorney General of Mexico, mentioned in a communiqué on 13 April 2011 that 16 of those arrested were municipal police officers in San Fernando.

"[67] The president of Mexico, Felipe Calderón, criticized the governors of the Mexican states for failing to certify and regulate their police forces, who often aid criminal groups in their activities.

[69] After the massacre of the 72 migrants, the discovery of the mass graves and the continuing violence between the Gulf Cartel and Los Zetas, fear so overwhelmed the citizens of San Fernando that more than 10,000 of them left the city.

"[80] With the arrival of Mexican federal troops and the creation of the military base, San Fernando's social fabric and normality have been recovering.

[82] According to Alberto Torres from El Universal, the people of San Fernando are resentful toward the government, from the federal level to the state and local ones.

[84] The massacre of the 72 migrants,[85] the mass graves with nearly 200 bodies, the assassination of the PRI candidate for state governor, Rodolfo Torre Cantú,[86] the murder of two city mayors,[87] the numerous prison breaks and killings,[88] the escalating violence in Tamaulipas and the lack of media coverage,[89] along with the political and police corruption,[90] have brought analysts to conclude that Tamaulipas may in fact be or become a failed state.

[91] Manuel Suárez-Mier, economist and drug war expert, believes that Mexico and Tamaulipas are "not failed states," since their economies are projected to grow starting in 2010, and the security measures stand in "a phase of reconstruction.