MEXICO CITY, Mexico - The sheer number of victims shot or beaten to death and buried in pits near the Texas border has shocked the Mexican public to the core.
But as the body count reached 183 this week - the biggest mass grave in Mexico's recent history - the government grappled with another painful detail: police were allegedly involved in the murders.
Federal agents have now detained 17 local officers from the municipality of San Fernando, accusing them of working with the Zetas criminal army in the massacres.
The allegations, which highlight a key problem in Mexico's crime wars, come as its Congress looks at two major bills to radically overhaul security.
The first would strengthen the role of the military, and allow the president to declare martial law in exceptional circumstances. The second would eliminate all municipal and state police officers in place of one unified federal force.
"Drug cartels have grown in power and we have to reform our institutions to face that threat," Rep. Gustavo Gonzalez, president of the Congressional security committee, told Global Post. "We are fighting criminals who have rocket-propelled grenades and heavy caliber machine guns. Local police are simply overwhelmed."
Gonzalez, a member of President Felipe Calderon's conservative National Action Party, said the military law would simply legitimize the use of the army, which is already deeply involved in fighting drug gangs.
The army would still have powers comparable to other democracies and martial law could only be used in certain regions in very exceptional circumstances, he said.
However, many civil rights activists are calling for the army to get back into their barracks rather than deeper into the fight.
During the four years of Calderon's offensive against drug gangs, soldiers and police have shot dead more than 100 innocent civilians, according to the government human rights commission.
"Calderon wants to be a strongman like Hugo Chavez," said Mercedes Murillo, a human rights activist in Sinaloa state, where soldiers killed five innocent women and children driving into a checkpoint.
"Soldiers are part of the problem not the solution. They are stealing and killing now illegally and Calderon wants to give them even more power to do this," Murillo said.
A draft of the military reform has been approved by the Senate and is currently being debated by the lower house.
The second bill, proposing a unified national police force, would entail the biggest changes to law enforcement since Mexico's Constitution of 1917.
That constitution established more than 2,000 different municipal police forces as well as 31 state forces, and several federal corps.
In the last four years, thousands of municipal policemen have been arrested working for drug gangs, sometimes as full-on assassins.
State and local police are also accused of involvement in actual attacks on federal police, showing a grave fragmentation of Mexico's government apparatus.
For example, in a 2009 attack that killed 15 federal police in Michoacan state, assassins were allegedly driven away in state police cars after their van got a punctured tire.
The bill supported by Calderon would combat this by putting all the police under a single command, a model that has had success fighting drug cartels in Colombia.
"We currently have 420,000 municipal police who are badly paid, poorly trained and vulnerable to corruption," Rep. Gustavo said. "Sooner or later we have to confront this situation."
The police reform bill is currently being fine-tuned in the lower house's constitutional commission.
U.S. State Department officials have encouraged reform of Mexican police, saying that institution building is a key to Mexico getting out of the hole of murder and kidnapping.
However, many activists are suspicious that a unified federal police would be a repressive paramilitary-style force and its officers could still be bribed by gangsters.
"You can change the uniform but they can still be corrupt," said Murillo, the activist. "We need a change from below, and the creation of police who respond to the community and really investigate."