In 2014, after the disappearance of 43 normalistas from Ayotzinapa in Mexico, Silván and other CentroGeo professionals joined the scientific advisory board on the case. During the search for the students, different civilian groups and government brigades discovered dozens of illegal graves. In less than 10 months, the Mexican Attorney General’s Office counted 60 sites and 129 bodies in the state of Guerrero. As a result of the searches, 300 illegal graves were discovered. Since then, the number of clandestine graves has only increased.
No one predicted the scale of this horror. The report “Search between pain and hope: discoveries of clandestine graves in Mexico 2020 – 2022”, explains with hemerographic data that during these two years, 1,134 clandestine graves were recorded, with 2,314 bodies and 2,242 remains. In proportional terms, Colima recorded the highest rate of illegal graves, with 10 per 100,000 inhabitants. Next come Sonora, Guanajuato, Guerrero, Sinaloa and Zacatecas.
In terms of number of cases, Guanajuato, Sonora and Guerrero stand out. These three entities represent 42% of the files. As of April 2023, a journalistic investigation by Quinto Elemento Lab reported that the number of illegal burials reached 5,696 clandestine graves, and that more than half of them were detected under the current federal administration.
Using his field of study, remote sensingJosé Luis Silván uses images captured with satellites, drones or planes, from which he extracts geospatial information using his knowledge of light physics, mathematics and programming. Multispectral and hyperspectral images capture underground information using sensors that record wavelengths of light imperceptible to the human eye, making them useful for research.
In 2016, during a first study carried out by CentroGeo researchers, they simulated burials with pig carcasses to assess the potential of using hyperspectral cameras in research and find out what information from the sensors was useful to them. Mexican researchers knew from research in other countries that successful detection with these techniques depends, in part, on the ability to recognize how carcasses (and their spectral images) change depending on the soils and climates.
The experiment was carried out on rented land in the state of Morelos. There, they buried seven animals and evaluated the light reflected from the ground at different wavelengths for six months. They concluded that a hyperspectral camera, which provides more than a hundred layers of data, has the potential to detect clandestine burials, although the technique is only effective three months after the burial. They tried to obtain the acquisition of a camera and a drone (worth P5 million) through the National Research Commission, but without success.
