Tucson, United States - The stench of death and decay hung over the morgue at the Pima County Office of the Medical Examiner where dozens of white body bags lay on metal trays on a warm February afternoon.
"We have 90 unidentified remains at the facility right now," Dr Greg Hess, the chief medical examiner, told Al Jazeera, pointing at body trays on the right side of the room. "Most of these people we believe to be undocumented border crossers."
About 100km from Hess' office, thousands of migrants have tried to cross the US-Mexico border through the US state of Arizona, which cuts through the arid Sonoran desert where summer temperatures soar above 40°C.
Many poorly equipped migrants, hiking for days on end, eventually succumb to the adverse conditions. Since 2001, the Pima County Office of the Medical Examiner has received more than 2,200 recovered remains of suspected migrants crossing the US-Mexico border.
|The morgue at the Pima County Medical Examiner's office in Tucson, Arizona [Felix Gaedtke/Al Jazeera]
Dr Hess unzipped a body bag with an "Unknown" name tag to reveal the limited contents within.
"Here, [this is] not uncommon. We have a skull and a little bit of property. What are the odds that we will identify this person in a very timely manner? Probably very small," he said.
In 2013, 168 migrant deaths were recorded in Pima County, and 95 of the bodies remain unidentified.
The Medical Examiner's Office routinely works with the Colibri Centre for Human Rights , an NGO that assists families to find remains of their loved ones who disappear at the borderlands.
The Colibri Centre was established amid the increasing discovery of unidentified remains of border crossers since the early 2000s.
In a tiny office, Chelsea Halstead, programme manager at the Colibri Centre, sifted through folders of missing persons' reports.
"People started calling here to try and find their loved ones who had died while crossing. They couldn't call the police because there were language issues or jurisdictional issues, or because the person in question wasn't an American citizen. In other cases, they were too scared to call the police," Halstead told Al Jazeera.
|US law enforcement officers often rely on data from SIM cards to try and identify bodies [Felix Gaedtke/Al Jazeera]
Halstead and her small team at the Colibri Centre take detailed missing person's reports from families calling in, then catalogue and compare them with profiles of unidentified remains that come into the Medical Examiner's Office across the hallway.
In some cases, they successfully find a match and help return the skeletal remains and property to bereaved families.
"Death is a social experience. Even though it's sad and it's difficult, it's social and it's important for the community," Halstead said. "When you don't have a body, you don't have that socially agreed upon narrative of what happened to this person. You don't get to collectively pass them along to the land of the dead."
Jasmin Morales' is one such family currently seeking help from the Colibri Centre. Jasmin's brother, Julio Cesar Morales, disappeared in 2009 while trying to cross from Mexico along with Jasmin and their father.
"My brother wanted to find work. In the town where we used to live [Tierra Blanca in Veracruz, Mexico], there is not much work," Jasmin told Al Jazeera over the phone.
|Bodies of unidentified migrants are buried at a barren corner of the Evergreen Cemetery in Tucson [Felix Gaedtke /Al Jazeera]
More than half of Mexico's population lives in poverty and the country has one of the highest murder rates in the world .
Under these conditions, many such as Julio make the perilous journey north in search of a better life.
Jasmin, her brother, and their father spent a week in the Sonoran desert. At the end of the journey, they lost Julio after an encounter with US Border Patrol agents one night.
"To be honest, I don't know what happened to my brother because the desert is something ugly," Jasmin said. "I'd love to find my brother alive, at least for my mother because she has the hope that he is still alive."
Jasmin, however, acknowledged the reality that her brother could be dead.
"They [Colibri Center] asked me for authorisation so they can look for him in the morgue. They told me it has been many years since he disappeared. So, it will be God's will. I don't really know if he is in prison or dead, but we want to know what really happened."
|The border wall in Nogales, Arizona is heavily guarded and effective at keeping migrants out [Felix Gaedtke/Al Jazeera]
Mexican migrants didn't always take the arduous Arizonan desert route to cross into the US.
Todd Miller, author of the book Border Patrol Nation : Dispatches from the Frontlines of Homeland Security, told Al Jazeera that border-security policies over the years have pushed people to trek through the unforgiving desert.
"The operations that took hold in the mid-1990s cut off traditional immigration routes in urban areas such as El Paso or Nogales or San Diego, creating a funnel effect. People were funnelled into areas that were supposed to be a deterrent, a lethal deterrent," he said.
In 1990, eight undocumented-person deaths were recorded in Pima County, compared to 225 in 2010.
Although unauthorised migration to the US along the Mexican border has decreased over the years, the US Border Patrol Agency has kept growing in size. Currently border enforcement costs $18bn each year.
Increased militarisation of the US-Mexico border explains the expanding budgets, Miller said. "Forward operating bases only used to be in Iraq and Afghanistan. But now you'll see it on the southwest borderlands."
|Volunteers of No More Deaths routinely conduct search-and-rescue operations to help migrants [Felix Gaedtke/Al Jazeera]
At the foothills of the Silver Bell mountains deep in the Sonoran desert, civil society group No More Deaths routinely conducts search-and-rescue operations to help migrants in distress.
On a recent February afternoon, a team of volunteers navigated through the vast landscape dotted with saguaro cacti.
"We get calls in distress that report someone in a group has started vomiting or started having diarrhoea. Often we also hear that people felt so sick that they were left behind," volunteer Genevieve Schroeder told Al Jazeera.
Schroeder showed Al Jazeera a recent recovery map where migrants were located.
"On the map the Silver Bell Mountains are like 70 miles [110 km] from the border, but the walking distance could be double that," she said.
"People weren't going this far a few years ago and now they are. They are now taking one of the longest routes that they could be forced to take," Schroeder said.
|On their walks of up to 200km through the desert, migrants often rely on water tanks for cattle to survive [Felix Gaedtke/Al Jazeera]
In 2005, the US Department of Homeland Security and Department of Justice implemented Operation Streamline, an initiative that subjects undocumented migrants to criminal prosecution, prison sentences, and deportation.
Schroeder said Operation Streamline has a direct impact on the number of deaths along the border.
"The deaths are happening further and further north of the country. People are putting themselves at higher and higher levels of risk, not seeking out rescue even when they are sick, even when they are lost, even when they have fallen behind because they may be facing a very lengthy prison sentence."
As the sun set over the desert, painting the sky in vivid shades of crimson, Schroeder's colleague Maryada Vallet expressed their organisation's collective frustration.
"The number of human remains that we find here every year is as if a Boeing aircraft had to crash in our desert every single year since the last 10 years. And we still can't figure out that this is a humanitarian crisis and not a law enforcement issue?"
Source: Al Jazeera