Philadelphians know by now that September 26 is the day Pope Francis touches down in the city for the World Meeting of Families' slate of weekend events.
But that day also marks exactly one year since 43 students in southern Mexico vanished, presumed dead in a case that remains highly disputed. Local activists originally from Mexico have pooled together resources to fly five mothers of the missing students from the rural state of Guerrero to Philadelphia to use this coincidence to draw attention to the case.
The five mothers have been given special seats for Pope Francis' remarks on immigration and religious freedom on Independence Mall, an event spokeswoman confirmed. The group now has its sights set on landing a private meeting with the pontiff to discuss what observers have called the worst human rights crises Mexico has faced in decades.
Angelica Gonzalez is one of the five mothers coming to Philly. She remembers that last interaction she had with her son, Jose.
"He came the night before, and said, 'Mom, I'll see you when I get back,' and we never saw him again," Gonzalez said through a translator. "What we want is the government to give us the bodies, or to give us the kids, because we know they have them."
Mexican officials say the 43 students were on a bus en route to a protest when they were intercepted by corrupt police, who handed the students over to a violent drug gang. The government says the gang killed them, incinerated their bodies at a trash dump, and then threw the remains in a nearby river.
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Yet a new report by an international human rights group contradicts key parts of that account. It says there's no way the bodies were incinerated — saying there couldn't have been a fire hot enough there to destroy that many bodies — and that the government knows more than it's telling.
So far, forensics specialists have recovered the charred remains of just two of the 43 students.
"The emotional level of these families is so enormous because in the background, in their hearts, they think there is a remote possibly that some of them might be alive," said Philadelphia resident Perla Lara through a translator.
Lara is one of the activists who's been communicating with the mothers of the missing students, and she launched an online campaign to pay for the mothers' visas, tickets and other transportation costs.
She says the mystery surrounding the students' disappearance has galvanized protesters all across Mexico.
Although it's been a year, there still are no solid answers. But theories are legion, she said.
"One is just being in the wrong place at the wrong time," Lara said. "This bus was a known drug transport, and they just happened to be there when there was this attack, or this raid. The other is definitely political. These were young people who were questioning the government."
The international report said it's possible that one of the buses the students were traveling in was carrying heroin or drug money, unbeknownst to the students. Still others say that's not likely. They were targeted, another hypothesis goes, because they were driving to a mass rally commemorating the 1968 Mexican massacre, when police killed scores of student demonstrators.
"This disappearance really shocked people," said Professor Matt Ingram, who studies Mexican criminal justice at the University of Albany in upstate New York. "The fact that they're young teachers in rural communities planning to dedicate their lives to teaching in rural communities. The fact that it reveals so much collusion among authorities and drug trafficking authorities at the local, state, even the federal level."
Philadelphia's Consul-General for Mexico Carlos Giralt-Cabrales said though local officials may have been involved, the corruption didn't reach the federal level. He said that the case is still being investigated and that more than 100 have been arrested.
"We all in Mexico regret terribly the disappearance of the students. We reject this kind of violence," Giralt said. "It's a complex case. There is conflicting information, but we're not satisfied and we're keeping the case open."
Giralt said the government is aware of the scathing human rights report and is using it as a guide. For now, though, it's sticking to the story that all the students died at the hands of drug gang members. The mothers of the students, meanwhile, feel voiceless.
And that's what the trip to Philadelphia is all about.
"We think that the voice of the pope is going to be the voice of them, of the people who don't have voice in our country. So we want the world to know about what's happening in Mexico," said another local activist Marcos Urbina.
Also part of the activist group is Fidel Moreno. He says Mexico has the world's second-largest number of Catholics in the world. If the pope calls on the government for justice, his words will carry weight.
"These mothers don't want revenge. They want justice. The idea is not revengeful, but to ask public officials to take responsibility for their role in this event," Moreno said.
Pope Francis has already called the students' disappearance a murder. But the activists want him to further shame the Mexican government for its handling of the case and to push officials to account for the missing students, or their remains.
Even if the activists are able to get the pope to deliver another pronouncement, Professor Ingram isn't hopeful that it will reroute the course of the investigation.
"The United Nations has spoken out against this, Human Rights Watch has spoken out, and an international group of experts has been very critical of the way the government has handled this case," Ingram said. "And none of that has seem to have any effect."