Microscopía de pelos como antecedente para la interpretación en química forense

Abstract

Forensic trichology is one of the most important sciences to solve crimes when there is the corresponding evidence to apply it. Its importance lies in its simplicity, hairs are easy to find in different parts of the body, both of the victim and the aggressor. Considering the above, the objective will be to analyze the microscopic characteristics of hairs in the laboratory for interpretation in forensic sciences. Due to this, the research has a mixed methodological approach, of cross-sectional and descriptive nature, whose objective consists in the analysis of the microscopic characteristics of hair in the laboratory, to provide an interpretation based on forensic sciences. The study group consisted of 75 individuals from which 10 samples were obtained through combing and extraction with tweezers. Zones corresponding to each anatomical area such as the axilla, lower extremities, pubic and occipital area were studied. Animal samples from dogs and cats were used as a means of comparison. After this, the main differences between animals and humans were identified through microscopy, as well as part of the hair growth cycle could be evidenced with the collected samples: length, color, odor and shape. At the same time, methods of cleaning and elimination of foreign substances such as blood and dust were applied, the results of which were compared to determine whether the soap solution or 10% potassium carbonate were more effective in eliminating impurities. Among the limitations was the inability to obtain samples from the female sex, since for aesthetic reasons they did not have enough hair in certain body regions, such as the pubic region and the lower extremities. In conclusion, the techniques used were collection, washing with dissolution and examination of the samples. The characterization and categorization were carried out using two macroscopic techniques and microscopy with samples from the axillary, pubic, lower extremities and occipital regions of different species. The differences between the anagen (hair plucked from the root) and telogen (hair falls naturally) phase of the collected hairs were evidenced, it is important for the determination and comparison of dubious and indubitable samples at the time of exclusion or inclusion of a prime suspect in a crime scene. The main recommendations for this study are to perform Barr's corpuscle analysis to determine the sex of hair while making a comparison between the direct method (use of adhesive tape) and Canada balsam for microscopic analysis.