The last day Luisa's son was seen alive was last year, around midday, as he was getting out of his car in the northern Mexican state of Chihuahua.
Three men were seen driving up to him in a white van. They drew their weapons, threw him to the ground, handcuffed his hands behind his back, and bundled him into the vehicle. One of the men took his keys, and they left with both vehicles.
Five months later, Luisa knows nothing more about her son's fate.
As soon as he disappeared, Luisa and her daughter-in-law tried desperately to do everything they could to find him. They reported the abduction to the state prosecutor's office and they visited every police station and hospital in the area, in case he had been charged with a crime or admitted as a patient.
At the prosecutor's office, Luisa was told that the staff there would examine footage from security cameras and analyse cell phone records for clues about her son's captors. Since then they've heard nothing. The family feel unsupported, in a suspended state of agony and grief, with no shred of certainty to console them.
I spent the morning hearing dozens of different accounts from relatives of Mexico's "disappeared."
In some cases, the victims' remains have been returned to them, months or years later.
But most often, family members said, they've been left with the anguish of not knowing whether their loved ones are still alive.
The numbers of the disappeared in Mexico are staggering. A government report leaked just before President Enrique Peña Nieto took office estimated that at least 25,000 have been abducted or have gone missing between 2006 and 2012. Several thousand more have been disappeared in the first fourteen months of Peña Nieto's presidency. Mexico's northern states of Chihuahua, Coahuila, and Nuevo Leon have been particularly beset in recent years by such abductions.
It's not clear, in most cases, who is responsible for these acts. The men who carried out the abduction of Luisa's son, for example, wore civilian clothes, drove an unmarked van with no licence plates, and carried a combination of handguns and rifles. No witness has identified them.
Mexico's drug cartels are presumably responsible for some of these disappearances. In many other cases, however, that's an unsatisfactory explanation. Like Luisa's son, many victims are men and women with families and regular jobs, with no obvious connection to organised crime.
Terrifyingly, the circumstances of some cases suggest the complicity, or even the direct participation, of municipal, state, or federal police or members of the armed forces. Such state involvement makes these acts more than mere kidnapping; they are enforced disappearances, crimes under international law.
If there is a common thread to the reports, painstakingly compiled by local human rights organisations and individual human rights defenders, it is that authorities have done very little to respond. In fact, they often react to reports of disappearances with indifference or outright hostility.
It is not unusual for families to be told to wait for 72 hours before they can file a report. That kind of waiting period might make sense in an ordinary missing-person's case, but not where an abduction is suspected.
We heard of one case in which authorities insisted on the 72-hour waiting period even though the victim's wife and young child had been abducted at the same time and then released several hours later. She repeatedly tried to convince prosecutors her husband had been taken against his will.
In many cases, public officials gratuitously suggest that the victims of abductions must be somehow involved in the drug trade. Statements like these are not only remarkably insensitive, they also imply that prosecutors are willing to turn a blind eye to crime when they think the victims are not deserving of state protection.
And when authorities do open investigations, they frequently make little effort to follow up on obvious leads.
It is unambiguously the state's obligation to investigate, prosecute, and punish criminal acts. When a state neglects these obligations, it is failing in its duty to protect its citizens. And when state officials repeatedly claim, like they do in Mexico, that "connections" to organised crime make thorough investigations impossible, it's no wonder that people accuse the state of being complicit in abuses.
Luisa and her daughter-in-law are learning to adjust to their loss, with difficulty. Her grandchildren, however, have had a much harder time. Her son's eight-year-old daughter has become withdrawn and now misbehaves. "At least with her, we can try to explain," she said. "But what do I say to my three-year-old grandson when he asks me every night why his father left him?"
Mexico must do better by Luisa and the tens of thousands of other relatives of the disappeared.
It should begin by developing rapid and effective mechanisms to search for the disappeared, immediately gathering all available evidence. It should increase collaboration between states and federal agencies. There is an urgent need to establish a national database of the disappeared and of unidentified human remains. Mexico must address persistent inaction on the part of prosecutors. And it must pursue with particular diligence, every report that suggests the involvement of its own officials in acts of disappearance.