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one of the keys to solving crimes in the region

by drbyos

On February 8, 2015, in the Almafuerte neighborhood of El Bolsón, they found the remains of a person. Due to the state of the body, it was impossible to determine who it was.. The samples that were taken and the DNA analysis allowed him to be identified. It was Yésica “Coco” Campos, who had been murdered at the end of December 2014 and the author had buried her body to hide the femicide. Cristian Maldonado, the young woman’s ex-partner, was sentenced in April 2018 to life imprisonment. The sentence was final.

The DNA study was key to determining that the young woman, whose family had reported them missing in early January 2015 had been murdered.

The work that the Bariloche forensic genetics laboratory team has been doing for more than a decade is essential for hundreds of cases that are processed in civil and family courts. But of vital relevance for investigations of criminal acts, when the perpetrators are unknown.

It is a scientific work that develops in silence. Which has its complexity. “It’s not so magical,” said the director of the Bariloche forensic genetics laboratory, Silvia Vanelli Rey.

“We always discuss the problems that genetic laboratories have to make prosecutors, the courts and the public understand that it is not always possible to obtain a genetic profile. It is not that one takes a sample, I put it in a tube and the photo of the author jumped out ”, he indicated.

But he stressed that “the burden of DNA evidence is currently of great importance.” Before, there was no such possibility. The testimonies of people who knew the people, photos where the mother and the alleged father were seen together, and other evidence were valued, but today the weight of the DNA result is decisive, for example, in trials of filiation.

The Bariloche forensic genetics laboratory collaborates in civil, family and criminal cases. Photo: Courtesy of the Public Ministry

However, there are gray areas. “Sometimes you think that the links can always be established and it is not so from a genetic point of view,” she said.

“Sometimes the biological relationships of people are very distant and the index obtained is very low, “because the chance of genetics means that they have received different things from their descendants. And that doesn’t mean they’re not linked,” he noted.

In any case, he clarified, “sometimes complementary analyzes such as mitochondrial DNA, paternal line by Y chromosome or X chromosome can be done.”

“That is why the Genetic Studies Bank created by the circle of the Grandmothers of Plaza de Mayo is so important. For this reason, there was such a big campaign, so that the relatives (of disappeared persons) bring samples ”, he highlighted.

He said that they use in their daily work DNA polymorphisms of autosomal markers, which are on autosomal chromosomes, and markers that are on sex chromosomes or mitochondrial DNA.

The links

“There are links that cannot always be established and it all depends on which people you have to make that link, what genetic information you have,” he said.

“If I have two grandparents, the partner of a person who is absent, I can establish the link with a possible grandchild because those parents do or do have 4 different possibilities of children because the genetic profile of the children of that couple can be assembled” , described.

“Now, if I have only one grandfather, it all depends on what line the grandson has. If the grandson is a boy, she will be able to do complementary tests, but if it is not a woman with a paternal grandfather, I will not be able to do additional tests because the paternal grandparents do not share sex chromosomes with the granddaughters. Yes, the paternal grandmother is going to share her x chromosome with her granddaughter, daughter of a son, ”she pointed out.

“It all depends on which actors you have to analyze the real possibilities of determining a link with an index that gives a certain certainty to a judge to rule,” Vanelli Rey summarized.

A little history

He recalled that the regional laboratories were created from a project promoted by the Council of Prosecutors, Prosecutors, Defenders and Advisors of Argentina and the Criminal Policy Council. The proposal was designed in 2008, but it was finalized in 2010.

Vanelli Rey recalled that she was asked “the importance of the Judicial Powers having their own laboratories and not having to send samples to private laboratories or institutions such as universities.”

He said that the Nation bought state-of-the-art equipment for the laboratories. The equipment arrived at Río Negro in 2010. The forensic genetics laboratory began operating in 2011, but it was inaugurated in 2012 due to the emergency of the eruption of the Cordón Caulle volcanic complex, in June 2011.

Vanelli Rey has been in the forensic biology service of the Judiciary since 2007, and since 2012 she has been the director of the laboratory after winning the contest.

They receive samples from the entire province of Río Negro and Neuquén. And they work for the federal justice established in the two provinces and Chubut.

“Our laboratory was closed only for the first 15 days of the pandemic. Then we started working because the criminal matter did not stop ”, he highlighted.

He said that before they sent the samples to the genetic fingerprinting service of the Faculty of Pharmacy and Biochemistry of the UBA, in charge of Daniel Corach.

The samples

Vanelli Rey commented that if the samples “are well preserved, depending on the type of samples, you can continue obtaining (profiles). Now if it is of the contact type, they are much more complex to analyze and more volatile, because there is very little material and over time the DNA degrades”.

Contact samples are those that arise from handling objects, such as ropes, a weapon, or the steering wheel of a car. “These are samples with a low concentration of DNA,” he asserted.

He said that a minimum amount of sample is needed in order to obtain a reproducible and reliable genetic profile. “This is the same as a cooking recipe. If you do not have the ingredients according to the recipe and in the quantity that is needed, the result will not be optimal, I will be able to repeat it ”, she graphed.

The work in the laboratory is in a team and in a meticulous way to contribute to clarify cases. Photo: Courtesy of the Public Ministry

“When a sample is processed, the first thing that is done is to purify the DNA, you take out the DNA that is in that support that can be a swab, a piece of cloth, a bone, an organ tissue, you extract it from there and then you quantify it, you see how much I have of that DNA extraction, ”he explained.

“If that amount exceeds the threshold, then we have to see how much it exceeds and how we continue with the processing,” he explained. If it is below it, it goes back or I take another sample if I have or I try to concentrate the sample to see if I get the threshold or I directly report that it could not be obtained because you do not have more samples and because there is not enough technique to get that well concentrated,” he said.

“For this reason, it is not always possible to obtain genetic material of analyzable quality.

It may also be that you get, but with degradation”, he highlighted.


“The fundamental thing is the taking of the sample, the preservation, that it be taken according to the conditions that are already established. There are protocols for how these samples should be collected, how to protect them, ”he said.

He said that everything has to come accompanied “with its chain of custody so that it is valid within the criminal process as evidence and so that one observes that there was no alteration.”

“When it arrives at the laboratory we know where it went, if it has been altered or not, the first thing one does is inform who required that analysis because it could be the prosecutor or the defense,” he commented.

“If when you open the envelope and you find, for example, that the swab inside that envelope is contaminated by fungi, that means that it was not properly preserved because it is contaminated and obviously degraded. So then the laboratory suggests that this is not a suitable sample to be analyzed, ”he explained. He clarified that situations like this “is something very occasional.”

He stressed that DNA studies “not only serve to arrive at a guilty verdict, they also serve, sometimes, to arrive at an acquittal.”

“Or even when they ask for an analysis, you collaborate with the prosecutor’s investigation to think that their line of investigation has to go another way, because that’s where I come from a budget that with the analysis you observe that it goes the other way,” Vanelli Rey commented.

There are cases where “it is assumed that the blood in the weapon corresponds to the victim or to the possible perpetrators of the act, but it may happen that you have an unknown perpetrator, but you want to preserve that genetic profile for later when one He wants to make a comparison that can be done”.

2800 samples processed last year in around 560 cases. Each sample takes 5 different tests. For this reason, they carry out some 9,800 reactions per year.

Some emblematic cases where DNA was key

At the end of August 2011, a trial court in Bariloche sentenced Cristian Hernández Oyarzún to 30 years in prison for a series of sexual abuses against women in Bariloche. It was known as the case of “the rapist from the west”, because all the abuses were committed in those areas of the city.

Silvia Vanelli Rey recalled that when the investigation began there was no identified perpetrator, but the prosecutors “had biological evidence and they sent us to do the analysis.”

“We received the first sample, we saved those profiles, we reported. The other cause arrives and we began to observe that there was the same profile, ”she recalled.

He said that in at least four cases they obtained “the complete profile of that second contributor who would be the author of the act.” “Prosecutors were told they were having the same genetic profile in those cases,” he noted.

The investigators obtained more evidence from other experts, plus the identikit, and thus it was possible to identify the author who is serving his sentence today.

In the investigation into the crime of Natalia Báez, which occurred in March 2016, the author could be identified by a DNA study. It was one of the most weighty pieces of evidence that the court considered to sentence Alejandro David Ramírez to 20 years in prison.

In August of last year, police officer Luis Ángel Díaz was sentenced to 18 years in prison for the murder of teenager Santiago Arriagada. The original accusation was for aggravated homicide by the bond. A DNA study revealed that the defendant was not his father and thus he avoided a life sentence.

DNA studies provide, above all, in investigations of cases of sexual abuse, where samples could be obtained for analysis, decisive evidence.

The inputs are imported

Silvia Vanelli Rey said that all the supplies used by forensic genetics laboratories throughout the country are of German or United States origin. Even down to the plastic material.

He explained that the plastic supplies that are used “must be free of DNA traces from any other individual. They have a process that is governed by an international standard -similar to the ISO- to be a producer of these plastic supplies, if you do not comply with it, you cannot sell”.

They work with resources from the Judiciary of the province. Despite the economic crisis, they have not run out of supplies because purchases are made in advance.

Security measures

To enter the laboratory, they take off the clothes they came in from the street, they both put on a nightgown, wear double gloves, a chinstrap, a cap, “as if you were going into the operating room,” described Silvia Vanelli Rey

There is a decontamination protocol, with UV lights that are turned on every day. All countertops and all equipment are cleaned. “There are a lot of processes that we do for non-contamination,” he assured. For this reason, Río Negro could not access the laboratory.

The laboratory has a director, two experts, three technicians and administrative staff. The professionals have profiles in Biology, Geneticists and Chemists. They are divided into administrative and technical-professional area.

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