Sandra Pérez Martínez, a 27-year-old biologist from Navarre, has carried out a research on Forensic Entomology, a discipline of Forensic Sciences in charge of applying the knowledge of arthropods -insects and mites- in legal investigations.

The doctor's research offers the first results on the species of mites that appear in decomposing animal organic matter and the insects (flies and beetles) that transport them to the corpses. "We have recognized at what stage of the life cycle the mites reach the corpses, how, when and how often, and we have also cited for the first time 24 species of mites in the Iberian Peninsula, and another 6 species of mites and 9 of insects in Navarra".

The interactions between mites and insects, the degree of specificity of the association, the identification of biological and ecological characteristics, phenology, abundance and frequency of occurrence, are other important contributions that Sandra Pérez has collected in her study.

The researcher points out that mites are being incorporated into forensic investigations - insects are usually studied - because they are a group of arthropods with a high diversity and are found in all environments. "They are abundant and frequent, participate in the faunal succession, and can be used to estimate the postmortem interval as indicators of the location and transfer of a corpse, and for the association of scenarios with suspects".

This research has focused on the Mediterranean region of Navarra and there are still no comparative studies in areas of the region with other types of climate. "It would be interesting to open the study to new areas to fully understand the diversity of species associated with organic matter in Navarra and to recognize if the species are the same in other climates and in urban, peri-urban and rural areas." 

For Sandra Pérez, the main difficulty faced by forensic investigators is the lack of comparative studies that allow them to draw conclusions when analyzing a criminal event. "Studies carried out at the local level are very scarce and punctual, and those from other regions do not usually provide extrapolable results since geographical differences can lead to variations in the diversity of species present and in succession patterns."