Mexico

It is typical for both collectives and law enforcement to search for bodies by walking sections of the desert or landscape, and many graves are discovered by accident.[12] Though drones are used, they are not common tools for these groups, suggesting that the easiest (though still difficult) way to find graves is to search on foot. One mother states that she stabs the ground with a stick as she walks, smelling the end for traces of decaying remains.[13] Drones providing an above-ground view are often not sufficient, as one group, Jalisco’s Search Commission, has equipped their drones with thermo-sensitive cameras to detect differing levels of nitrogen and humidity levels in the soil, which could potentially lead to the discovery of graves.[14] With all of this in mind, moving forward with a project that relies on satellite imagery may prove difficult, as Cartels dispose of bodies in ways that are difficult to find. That being said, some groups are finding new methods to aid in the discovery of graves that rely on satellites and maps, which could aid this project if it continues forward.

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From Above:

A project undertaken by Mondragón, Diaz, Reyes, and Cárdenas at CentroGeo has taken a different approach for identifying mass graves with satellite imagery and coordinates of sites that have already been found.[15] The group made a request to the Attorney General of the State of Baja California (FGEBC) for the coordinates of found sites and marked those on a map. Using this information, they aim to predict where new clandestine graves will be located in the same region (in this case Baja California). This approach relies on three factors: “Point pattern analysis, accessibility combined with visibility analysis, and hyperspectral analysis.”[16] Their hypothesis is that, based on these three factors, researchers and law enforcement agencies may be able to predict which regions Cartels will return to or use in the future, thereby shrinking the potential search area and making the process easier for those searching on the ground.

First, point pattern analysis refers to the idea that if several graves were found within close proximity to one another, then it can be assumed that their placement is not random. In this way, new graves in the same area could be found, or the search area at least narrowed down. The second factor relates to the tendency of Cartels to choose private sites, such as those obscured by the forest or rough terrain. That being said, accessibility for the quick disposal of remains is also a requirement. Therefore, sites that meet both needs may lead to the discovery of graves and should be prioritized during searches. An example of this is evident in the grave site mentioned above near Sendero de los Fresnos Street in Guadalajara. The site is accessible by the street, yet private enough to remain hidden, as the ravine is difficult both to see into and to access.

The final factor relates to detecting the presence of increased levels of nitrogen, which suggests decomposition. Through the use of Red-edge Chlorophyll Index (RECI), the decomposition of animals was detected through an increased production of chlorophyll in the plants in the surrounding area. RECI can be computed from the images produced by satellites Sentinel-2A and Sentinel-2B from the European Space Agency’s Copernicus program. CentroGeo created an index to “account for the increase of RECI from images acquired by the Sentinel-2A/B constellation from 2016-2020 in Baja California.”[17] Though other human activities can impact the levels of nitrogen, such as fertilized fields, it can be used to detect the presence of large graves, as demonstrated in their article with a grave found in Tijuana.