In 2014, after following the disappearance of 43 Ayotzinapa normalists in Mexico, Silván and other CentroGeo specialists joined the scientific advisory board dealing with the case. While searching for the students, various civilian groups and government brigades discovered dozens of illegal graves. In less than 10 months, Mexico’s Attorney General’s Office counted 60 sites and 129 bodies in Guerrero state. As a result of the searches, 300 illegal graves were discovered. Since then, the number of secret graves has only increased.
No one expected the scale of this horror. Report“In Search Between Pain and Hope: Finds of Secret Graves in Mexico 2020-2022” shows based on hemerographic data that during these two years, 1,134 secret graves were registered, containing 2,314 bodies and 2,242 remains. Proportionally, the highest rate of illegal graves was recorded in Colima – 10 per 100,000 inhabitants. It was followed by Sonora, Guanajuato, Guerrero, Sinaloa and Zacatecas.
Guanajuato, Sonora and Guerrero stand out in terms of the number of cases. These three entities account for 42 percent. records. By April 2023, a journalistic investigation by Quinto Elemento Lab found that the number of illegal burials had reached 5,696 secret graves, more than half of which were discovered during the term of the current federal administration.
When hiring your field of study, remote sensingJosé Luis Silván uses photos taken by satellites, drones and planes, from which he extracts geospatial information, using knowledge of lightweight physics, mathematics and programming. Multispectral and hyperspectral imagery captures subsurface information using sensors that capture wavelengths of lightweight imperceptible to the human eye, making them useful for searches.
In 2016, in the first study by CentroGeo researchers, they simulated burials with pig carcasses to assess the potential of using hyperspectral cameras in searches and find out what information from the sensors was useful to them. Mexican researchers knew from research in other countries that successful detection using these techniques depended in part on the ability to recognize changes in carcasses (and their spectral images) in different soils and climates.
The experiment was carried out on rented land in the state of Morelos. Seven animals were buried there and lightweight reflected from the soil at various wavelengths was assessed for six months. They concluded that a hyperspectral camera, which provides over a hundred layers of data, could detect secret burials, although the technique is only effective three months after the burial. They tried to arrange the seizure of the camera and drone (worth 5 million pesos) through the National Search Commission, but to no avail.