Hyperspectral Imaging: A New Tool In Mexico's Search For The Disappeared

By John Oncea, Editor

Geospatial tech, including hyperspectral imaging, aids Mexico’s buscadoras in locating clandestine graves, offering hope to families of the disappeared.

Hyperspectral imaging is being used in various fields, including environmental monitoring, food quality control, life sciences, and the military. Essentially, anywhere a detailed analysis of a material’s chemical composition is needed through its unique spectral signature.

It’s also being used in niche areas like analyzing art and historical artifacts to identify pigments and restoration details, detecting hidden signatures on paintings, monitoring coral reef health, identifying specific pollutants in water bodies, mapping mineral composition in geological samples, analyzing plant stress at the cellular level, and inspecting pharmaceutical tablets for consistency in chemical composition.

And, it’s being used by las buscadoras, or the searchers, in Mexico to locate the remains of missing persons, often by combing through garbage dumps and suspected clandestine graves, to bring closure and justice in the face of widespread disappearances in the country.

Mexico’s Missing Persons Problem

Mexico has a long and harrowing history of missing persons, writes Faces Of Conflict. “Officially 116,000 people have gone missing and have never been recovered since 1952, although the actual number could be far higher.

“The phenomenon has increased exponentially since 2006 when then newly inaugurated President Felipe Calderón ratcheted up the country’s ‘war on drugs.’ During his six-year term, over 40,000 people went missing, a figure roughly eighteen times higher than the entire number of people who had disappeared over the previous four decades.”

The situation has only worsened since then. During the administration of President Enrique Peña Nieto (2012–2018), nearly 100,000 people were reported missing. Under the presidency of Andrés Manuel López Obrador (2018-2024), that number has increased by an additional 13 percent, with almost 30,000 disappearances recorded in 2023 alone.

This sharp rise in disappearances is closely tied to escalating violence across Mexico. During López Obrador’s six years in office more than 185,000 homicides were officially documented, surpassing the toll of any previous administration.

As criminal groups vie for territorial control, more people become vulnerable to violence. Many of these groups resort to kidnapping and disposing of their victims in clandestine graves with several factors driving it.

Disappearances serve as a method of punishment, prolonging the suffering of victims’ families while sending a chilling warning to local communities. Additionally, hiding bodies allows criminal organizations to carry out extreme violence without significantly increasing official murder statistics. This tactic is particularly relevant in areas where authorities and criminal groups have informal agreements to limit overt violence, as reported by Crisis Group.

Improved recordkeeping may also contribute to the rising numbers. Since the inclusion of enforced disappearance in the Penal Code in 2017, more cases have been officially reported. Under Mexican law, enforced disappearance refers to crimes involving individuals connected to the state, such as police or military personnel, whereas disappearances committed by civilians are classified as simple disappearances.

Las Buscadoras, Other Groups Spark Change

“After decades of ignoring the plight of the disappeared – or, failing that, blaming the victims for what befell them – in the 2010s, Mexican government officials began to deal with the issue more seriously,” Faces of Conflict writes. “This was in no small part because of the creation of the first buscadoras chapters in 2009.”

By 2012, advocacy efforts pushed the Mexican Congress to pass the Law on the National Register of Missing and Disappeared Persons, mandating a public record of disappearances and outlining institutional responsibilities.

The crisis deepened in 2014 when 43 students from Ayotzinapa, Guerrero, vanished in one of Mexico’s worst modern atrocities. In response, Congress passed the General Law on the Forced Disappearance of Persons, leading to the creation of the National Search Commission, which coordinated local and federal efforts to locate the missing. The law also established the National Centre for Human Identification (CNIH) to compare DNA from morgues and mass graves with relatives’ samples, aided by U.S. funding. However, President López Obrador later gutted the CNIH, returning identification duties to public prosecutors.

López Obrador further angered search groups by attempting to lower official disappearance figures. In June 2023, his administration announced an audit of the missing persons list, leading to the resignation of Karla Quintana, head of the National Search Commission, who warned the government was manipulating data. By December, López Obrador claimed only 12,377 confirmed disappearances, despite families still searching for thousands of missing loved ones.

As the government retreats from addressing the crisis, las buscadoras persist. Since 2018, the Hasta Encontrarte collective in Guanajuato has located 139 deceased and 12 living individuals. The Rastreadoras de Ciudad Obregón in Sonora found 150 bodies between 2019 and 2022. “We have shown the authorities that those who seek, find,” says Nora Lira, who founded the group after her daughter disappeared.

The Searchers’ Quest For Miracles

Madres Buscadoras Sanora is one of 230 chapters of mothers and volunteers operating throughout Mexico, according to NPR. One of the group’s members, Cecilia Flores, has been searching for her sons Alejandro Guadalupe Islas Flores, who went missing in 2015, and Marco Antonio Sauceda Rocha, who disappeared four years later. After all this time, she hasn’t given up hope that she'll find them.

“Searching for the missing can be intimidating,” writes NPR, adding Madres Buscadoras sometimes has to ask the cartels for permission to search certain areas. So why do it?

“I risk my life, but what won't we do for our children?” Flores said.

NPR followed Madres Buscadoras as the group followed up on a tip about human remains possibly being on land at the base of the volcano. “A local police officer stopped the group as soon as it entered the area,” NPR writes. “The officer instructed them to park their cars and said they could only roam at a radius of about 30 feet.”

The officer told searchers the area was known for being a clandestine crematorium for dogs but one of the volunteers – Virginia Ponce – said the group was there in part to prove human remains existed amongst those of the dogs.

Ponce, whose son Víctor Hugo Meza Ponce disappeared in 2020, is part of the Madres Buscadoras chapter in Jalisco but joined Flores on this search. "I'm here to support the women of Mexico because we all feel the same pain and we're here to help one another," Ponce said.

Restricted to the 30-foot radios, searchers “got out their drone and flew it through the desert-like terrain and over the alleged grave site. Though not much is visible through this eye in the sky.” Thirty minutes after the search began Erika Estrella Omega, the local police chief, arrived and, flanked by a dozen officers, shut the search down.

The group moved on to a site about half a mile away and shortly after they began digging unearthed a tattered shirt, a belt, and a sock from a six-foot-deep hole.

“While Flores dug at the second search, she got two calls in four minutes,” writes NPR. “First, a woman called to inform the group that her son who had been missing for four months was found alive. A second woman pleaded for more photos of a man whose remains were found in Hermosillo, Sonora.”

Using Geospatial Technology To Aid In The Search

To address this humanitarian emergency, researchers are increasingly turning to geospatial technologies encompassing tools that collect and analyze spatial data, offering critical insights into the locations of clandestine graves. According to Wired, this includes scientists from the Center for Research in Geospatial Information Sciences (CentroGeo) who use technology and data analysis to service the searches. “I never thought I would have to work on this, but if this knowledge is of any use, now is the time to show it,” says José Luis Silván, a geographer at CentroGeo.

Initially focusing on satellite data for environmental studies, these scientists have redirected their expertise toward humanitarian applications, employing drones with advanced imaging systems to detect burial sites. Their work involves analyzing geographical patterns and environmental markers indicative of clandestine graves, thereby refining search protocols and improving the efficiency of ground searches.

Hyperspectral Imaging: A Powerful Tool

Hyperspectral imaging stands out among these technologies because it can capture a wide spectrum of light across numerous narrow bands. This capability allows for the detection of subtle changes in soil and vegetation that may signal the presence of buried bodies. For instance, decomposing organic matter can alter the chemical composition of surrounding soil and affect plant health, changes that hyperspectral sensors can identify. Researchers have conducted experiments using simulated burials with pig carcasses to evaluate the effectiveness of hyperspectral cameras in detecting these changes, with promising results.

The success of hyperspectral imaging is amplified when integrated with other geospatial methods, adds ResearchGate. A study assessing various geospatial models found that factors such as proximity to urban areas, nighttime light brightness, and population density are significant predictors of the occurrence of clandestine graves. By combining hyperspectral data with analyses of these variables, researchers can prioritize search areas more effectively. This multidisciplinary approach enhances the accuracy of locating potential burial sites, thereby optimizing resource allocation during search operations.

Practical Applications and Collaborative Efforts

The practical application of these technologies has already yielded tangible benefits, Just Security reports. In Jalisco, the FOUND Project demonstrated that drones equipped with multispectral cameras could replicate and enhance the methodologies used by local search groups. This technological integration not only increases the efficiency of searches but also reduces the physical and emotional toll on volunteers, many of whom are family members of the disappeared.

Collaborations between scientific communities, civil organizations, and governmental agencies are crucial for the continued development and implementation of these technologies. Such partnerships facilitate the sharing of data, refinement of search protocols, and training of personnel, thereby strengthening the overall capacity to address the crisis of missing persons in Mexico.

Challenges and Future Directions

Despite the advancements, several challenges persist. According to CoLab, the vast and varied terrain of Mexico, coupled with limited access to certain areas due to security concerns, poses significant obstacles. Moreover, the high cost of advanced geospatial equipment and the need for specialized training can be prohibitive.

To overcome these challenges, ongoing research is focused on developing cost-effective solutions and user-friendly platforms. For example, the Espacio Clandestino platform leverages Google Earth Engine to provide accessible geospatial analysis tools for identifying potential grave sites. Such innovations aim to democratize the use of advanced technologies, enabling broader participation in search efforts and fostering a more coordinated response to the crisis.

The integration of geospatial technologies, particularly hyperspectral imaging, into the search for Mexico’s missing persons represents a significant advancement in addressing this pressing humanitarian issue. Through continued collaboration, technological innovation, and dedicated research, there is hope for providing closure to countless families affected by this tragedy.