Estudio comparativo del líquido preseminal y seminal aplicando métodos de orientación y certeza para pericias químicas forenses en casos de delitos sexuales

Abstract

The State Attorney General's Office receives complaints for sexual crimes, most frequently among women; children and adolescents predominate in this age group. To resolve these cases, various expert methods are used to search for biological clues at the crime scene or in the victim. Among the methods used are orientation techniques that provide important information to locate traces in textile clothing or other types of material found at the crime scene. To confirm the evidence, the certainty method is applied, confirming the presence of blood, saliva, seminal remains or other relevant element in the scene. However, these types of fluids are not the only ones present at crime scenes; traces of precum can also be found, which are not given relevance due to the minimal amount present. Therefore, the present investigation aims to compare the pre-ejaculatory and ejaculatory fluid through an orientation and certainty test for forensic chemical expertise in cases of sexual crimes. The methodology used has a descriptive and qualitative approach, with the participation of 26 volunteer students from the Technical University of Machala, applying inclusion and exclusion criteria after accepting informed consent, the study was carried out. The statistical analyzes of sexual crimes due to rape in the period (2014-2022) revealed a higher prevalence of complaints in the province of Pichincha, of the 95.54% of complaints made, only 4.27% reached a resolution, this is due to problems in the investigation or lack of evidence analyzed at the crime scene. Therefore, the following study focuses on the comparison of seminal and pre-seminal fluid, obtaining greater relevance for seminal fluid. These results were analyzed with orientation and certainty tests. In the orientation test, 3 types of supports were used, analyzed with ultraviolet light, with the paper towel support achieving the best results. After that, the certainty test was carried out through microscopic analysis with methylene blue and Diff-quik staining, the latter being the one that demonstrated the greatest number of positive samples. According to the findings of the investigation, we suggest not ruling out the analysis of the precum since it was able to show the presence of male sexual cells that can contribute to the resolution of sexual crimes. In cases of azoospermia, other methods established for sexual crimes and other types of fluids must be carried out to prevent reported cases from going unpunished. In conclusion, the tests used allowed us to compare precum and seminal fluid through UV and optical microscopy, Diff-quik staining allowed a better morphological evaluation of the sperm unlike methylene blue. It is recommended to continue the research with a greater number of participants and in judicial cases to maintain a strict chain of custody from the moment the sample is taken, especially in cases of azoospermia.