Banco de Dados de Perfis Genéticos Y específicos como Ferramenta na Investigação de Crimes Sexuais

Abstract

Given that the vast majority of sex crimes involve men as crime perpetrators, molecular markers Y-STR can be valuable in the criminal investigation process. The Y chromosome has been promising when the objective is to identify the male DNA source in the analyzed sample, especially when it is presented in small quantities or mixed with genetic material from female origin, which are rather typical in samples of vaginal smears from rape. In addition to the fact that sexual assaults have a recurrent pattern, constituting serial crimes, the present work proposes the creation of an in-house Database of Genetic Profiles Trace for YSTR markers (BVPG-YSTR), in order to elucidate sex crimes occurred in the state of Goiás (Central Brazil). The study documented 2,109 cases of sexual violence with a positive result for cytological spermatozoa research, registered in the Scientific Police of Goiás State, comprising the period of 2004 to July 2018. DNA extraction was given with differential lysis by organic method or with the use of PrepFiler Express ™ (Applied Biosystems®), DNA quantification was performed by Real-time PCR and amplification with AmpFlSTR®Yfiler ™ multiplex kits (Applied Biosystems®) or PowerPlex® Y23 (Promega) or Yfiler ™ Plus (Applied Biosystems®). The amplification products were separated by capillary electrophoresis in the ABI 3500® Genetic Analyzer (Applied Biosystems®). Of the total of 2,109 analyzed cases, 54.7% were perpetrated in the circumscribed surroundings of Goiânia. The highest number of records occurred in 2009. And in 55.7% of the cases, the samples collected came from the victim's vaginal duct. Samples related to 271 cases were submitted to DNA exams. Considering the results of the DNA tests, in 252 cases of sexual assault were obtained the haplotypic profiles of the rapist, and 168 came from occurrences in which there were no suspects. The insertion of 252 haplotypic profiles in the BVPG-YSTR resulted in 85 matches between traces of crimes of sexual violence, involving 17 aggressors and 55 victims, resulting in a coincidence rate of 33.7%. In 18.1% of the cases, coincidences were reported exclusively by the BVPG-YSTR. Among the serial crimes identified by the BVPG-YSTR, in most cases the perpetrator raped on two different occasions. The temporal distance between intermittent cases ranged from 0 to 2151 days. The analysis of the geographical distribution of serial crimes showed that, as a general rule, there is no displacement of the sex offender. In the analysis of the 252 cases of sexual assault, 82 were perpetrated against vulnerable victims. The discrimination capacity (CD) of the set of 17 Y-STR markers for the population of Goiás was 0.9819. The panels with 23 and 27 Y-STR markers showed CD equal to 1. Five false matches were observed among in 277 samples which were submitted for analysis using 17 YSTR markers. Thus, the usage of BVPG-YSTR looked promising as far as aiding criminal investigations is concerned.