University of São Paulo experts opine DNA- a milestone for forensic science
Many series and films deal with the investigation and resolution of criminal cases and the search for fingerprints is one of the central points in the examination of the crime scene. However, the search for traces that contain DNA is as important as the famous fingerprints. For forensic science, which is responsible for the investigation, analysis and study of crimes and their evidence, the advent of the use of DNA in criminal cases was a fundamental milestone.
“There is a turning point , a moment when there is a change in every type of investigation: it was when, in 1986, in England, there was the murder of two 15-year-old girls. These murders took place in different locations but had the same modus operandi . The analysis of the DNA obtained from the material from the vaginal secretions of the two young women showed that the same person had committed both crimes, and from there the police collected the material from residents of the region and found the individual. This moment is a turning pointbecause, from then on, investments were made in setting up Criminal Investigation Laboratories all over the world”, comments Professor Ivan Dieb Miziara, from the Department of Forensic Medicine, Medical Social and Work Ethics at the USP School of Medicine and also a member of the National Academy of Legal Medicine.
Process
To collect trace DNA from the crime scene, the instrument used is the swab , which is a type of cotton swab that is usually longer. Professor Jesus Antonio Velho, of Forensic Science and Criminalistics at the Faculty of Philosophy, Sciences and Letters of Ribeirão Preto at USP and also a federal criminal expert, explains how this procedure is carried out: “The DNA is found at the crime scene, in the group of so-called biological traces, which are those derived from living organisms: they can be evident and clearly associated with the criminal action, such as blood on the murder weapon, on a knife, or as subtle as epithelial cells in a glass of wine. Once located, in general, the collection is made by rubbing the swab in the areawhich is then duly packaged and sent to the forensic genetics laboratory“.
Still on the process of obtaining the genetic material, Miziara adds: “It is very simple, very easy and it is even easy to store for future investigations. Mainly because it’s always a comparative exam: you take material from a crime scene or from a victim and it has to be compared with the possible suspect. The comparison is normally made through blood, which is the gold standard material for extracting DNA and genetic profile of individuals. It is an extremely reliable test and is a very important aid to criminal investigation, where medical expertise and criminal expertise make an important contribution to justice and criminal investigation.”
In the 90’s, shortly after the first use of DNA in solving a criminal investigation, this tool began to be used in Brazil, with the construction of specialized laboratories. Miziara comments that one of the difficulties in using genetic material as a differential factor in research is still the lack of laboratories, due to the high cost, and also the scarcity of specialized professionals in this area.
Genetic profiles in Brazil
The United Kingdom pioneered the creation of an agency responsible for concentrating the collected genetic profiles. Currently, he has more than 5 million profiles, according to data from the UK National Database table. Brazil, even with the aforementioned obstacles, has a considerable Genetic Profiles Bank, containing more than 175,000 registered profiles.
The decree that established the BNPG was 7950, of March 12, 2013, which is quite recent when compared to the United Kingdom, which appeared in 1995. As for the way to increase the number of profiles, Professor Jesus Antonio Velho explains: “Unfortunately, most crimes do not have a suspect immediately identified and, without the suspect reference sample, there was no way to compare these profiles. The Genetic Profiles Database came precisely to solve this problem. In the context of the investigation, here in Brazil, the DNA of those convicted of intentional crimes committed with serious violence, as well as that of those convicted of crimes against life, against sexual freedom or other crimes in which the determination comes by means of court order”.