DNA exam application in crime elucidation / Aplicação do exame de DNA na elucidação de crimes

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The wide application of the DNA exam in paternity investigation led to the massive divulgation of its efficiency through the communication channels, earning it a reputation of infallible result, and jeopardizing the credit of older analytical methods. While focused by the media as the most supreme technique, several limitations were omitted regarding its use in criminal matters, such as its high cost and the complexity of technical processes demanded for trustworthy results. The theme is still discussed in a superficial way among the Brazilian juridical scenario, which leaves the law related individuals with a lack of technical and scientific knowledge required to the interpretation of results offered by DNA exams. The goal of this report is to, in a way, diminish this technical and scientific gap and clarify the real accomplishments and limitations of this technique, while applied to forensic investigations as an auxiliary alternative to crime solving and people identifying. We begin with the study on the evolution of the techniques applied in Legal Medicine to human identification, discussing the surpass of DNA analysis in relation to other traditional exams. The development of Molecular Biology is featured with basis on the DNA structure and the way the genetic information is transmitted, followed by the polymorphisms detection in this molecule and obtainment of specific genetic patterns which have been used for identifying suspects of sexual crimes; identification of crime and catastrophe victims, and in the establishment of a link between suspects and crime scenes, one crime scene and another, and a wound object and a victim. Great emphasis is given to the collecting of material and precaution used to ensure the custody of samples to be analysed, enhancing the ethic and legal aspects involving the collection of biological material of suspects brought to light as per the Brazilian Law. Laboratory procedures utilized to the extraction, amplifying and detection of DNA analysed material are outlined, and statistics methods applied to the correct interpretation of results and existing recommendations to elaborate the expert report, and to the necessary quality control of DNA analysis. Several aspects referent to the use of information about DNA are discussed, as whether in relation to its social repercussions or as a penal proof, through the characteristics of its contradictory and real value to elaborate culpability. An expert essay formulated at the São Paulo Criminal Institute DNA Laboratory is presented along with a statistics study on the technical efficacy of samples analysis made in that lab. The conclusion is that the DNA analysis, despite being a powerful tool, is far from being a sine qua non condition in forensic studies. The DNA proof must always be considered within an ensemble of various evidences, and the role of the legal genetic expert is not to make presumptions of culpability of innocence, but to provide accurate information to help the applicable law.

ASSUNTO(S)

medicina legal molecular biology exame de dna dna forensic exam dna´s proof value legal medicine crimes identificação criminal perícia (processo penal) human identification prova (processo penal)

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