Many times, the victims in Mexico's drug war simply disappear. Just a few miles outside this quaint tourist town filled with silver jewelry shops, Mexican authorities discovered where some ended up.

For months, maybe for years, feuding drug mafias have unloaded their bound-and-gagged victims from pickup trucks and car trunks and thrown them down a deep, dark hole. It is one of the most macabre spectacles in a drug war that each week brings news of greater barbarities.

For the past year, locals here reported rumors of strange vehicles on the road at night. And in May, the Mexican military arrested some gunmen who revealed under pressure the existence of a mass grave, which is the largest ever found in Mexico.

It does not look like much from the surface. A simple concrete-block building, tagged with a crawl of graffiti, covers the entrance to a ventilation shaft designed to feed air into nearby silver mines. The mines have been closed for three years by striking workers demanding better pay from the owner, one of the biggest corporations in Mexico.

Subterranean killing field
State investigators rappelled down the 15-foot-wide shaft through darkness to reach the bottom, 50 stories down, where they found a cold, dripping-wet cavern filled with noxious gases. As they panned their headlamps around the cave, they found a subterranean killing field. Initially, they thought there were 25 dead, then 55. But as they struggle to reassemble the bodies at the morgue in the capital city, they think they have found the remains of 64 people.

"It was like a quicksand, but filled with bodies," said Luis Rivera, a young chief criminologist, who was one of the first to descend into the mine.

"We were stepping on them," Rivera said. "It was a very challenging working environment."

The recovery of the remains took five days, and the work of identifying the dead has just begun, a task made more difficult by the fact that some cadavers were mummified, others were dismembered by the fall and at least four of the victims had been decapitated.

"There are headless bodies, but some of the heads don't match the bodies," Rivera said.

Based on examinations of wounds, investigators said it also appears that many of the victims were alive when they were thrown down the mine shaft.

A few might even have survived the fall before they succumbed to injuries.

Medical examiners have identified only eight bodies so far. One was Daniel Bravo Mota, a Guerrero state prison director who had gone missing in late May.

As Mexico fights a U.S.-backed war against the powerful criminal mafias, the news headlines continue to numb. The media reported on the mass grave for a few days and then moved on.

But increasingly, the violence is reaching popular tourist spots — safe zones that before seemed off-limits to the killers.

In the resort city of Cancun, authorities last week uncovered the decomposing remains of 12 people lying in nearby sinkholes, known as cenotes. Earlier, they had discovered six others. Three were found with their hearts removed. Some had the letter "Z" carved onto their abdomens, a clue perhaps left by the paramilitary drug cartel known as Los Zetas.

In the Pacific Coast state of Nayarit, just north of Puerto Vallarta, the governor, Ney González Sánchez, abruptly suspended the school year three weeks early as anxious parents, upset by rumors and threats on social media outlets such as Twitter and YouTube, demanded action but feared attacks on children.

The hotel zone in Acapulco has been the scene of hours-long gun battles between the military and cartel members, who have used grenades in the fights. A cartel leader was found and killed by Mexican marines in a luxe condo in colonial Cuernavaca. In Michaocan, where tourists flock to see the annual migration of monarch butterflies, cartel gunmen ambushed a convoy of federal police officers, killing 15 of them two weeks ago.

Taxco was supposed to be a safe haven. Built to mine silver and developed in the early colonial period by the soldiers of conquistador Hernán Cortés, Taxco today is a hill town of red tile roofs, restaurants with sweeping views and lots of shops selling silver jewelry to no one these days.

A few blocks from the central square, neighbors declined to speak much about an attack in which military forces, acting on a tip last week, killed 15 cartel gunmen at an apartment house on a quiet street. The street-level apartment, its windows shot out and walls pocked with bullet holes, still smells rank with blood.