Mexico City—Roberto Galván lifts his hand from his hip with gravitas, his eyes softening as he removes his square, bifocal glasses. His skin is blotched underneath the lenses, grey patches decorating the space between the wrinkles. His face is tired, his voice full of sorrow. “Should I tell you about my case?” he asks me. He leans forward and takes a deep breath.

In January, Galván’s son disappeared. The 34-year-old, who lived in Monterrey, had taken a brief holiday in General Terán, a tiny town just nearby. One day, while Roberto was sitting in the central plaza, perhaps taking in the warm air and sun after weeks of rain, several armed men began to surround the square. As his father would later learn, these men took young Roberto away. Galván has not heard from his son since.

When he disappeared, Galván Jr. became one of the more than 5,000 people who Mexico’s human rights commission, a non-partisan government body, say have met a similar fate in the country over the six-year assault President Felipe Calderón’s government has waged against the country’s drug cartels. Taken away by criminal gangs looking to induce fear, narco-traffickers seeking new recruits, or rogue security forces with other motives, these people have simply vanished. And disappearances are just one of the many tragedies that have clouded Mexico’s narco wars: Every day, pictures of corpses are plastered on newspaper front pages. Official figures estimate that some 40,000 souls have perished since 2006, and most analysts believe that this figure is a minimum, based only on the deaths that have been reported by the police and in the media. According to the government, most of these people were criminals.

For months, Galván, who insists that his son was never involved in any criminal activity, has been speaking to everyone he can think of about his case—neighbors, policemen, politicians. In early June, however, something changed: Suddenly, he wasn’t alone in speaking about his loss. For the first time, wider Mexican society started having a conversation about how the country—which has the world’s eleventh largest economy and one of the richest political histories in Latin America—has deteriorated into brutality. And it was all thanks to protests, led by a movement dubbed “the Caravan for Peace,” that thousands of people have joined. Many of them, like Galván, are family members of the drug war’s victims.

Back in January, when Galván approached authorities about his son’s disappearance, he was met with blank stares and open admissions that the police couldn’t or wouldn’t do anything. He grew so frustrated with the evasion that he undertook his own investigation. He traveled to General Terán, where everyone knows everyone. He sought out a local priest, who helped him contact restaurant owners and motel managers, with whom he spoke and pieced together his son’s last steps. After talking to witnesses who were in the square the day his son was taken and who saw the attackers, Galván believes that Roberto Jr. was apprehended by the police for unknown reasons. The truth about what happened is unlikely ever to be known. Criminal bands and police often mix, and kidnappers and assassins rarely identify themselves after a crime. “We know where he stayed, what he ate, and who had taken him,” Galván said. What’s missing, of course, is the answer to the most important question of all: where his son is today.