The expert testimony of the repression of December 19th and 20th made by a scientist at the request of Justice

On December 19 and 20, 2001, CONICET physicist Willy Pregliasco did nothing but watch television. The images on the screen of what was happening fifteen hundred kilometers away from his home, that cocktail of social anger with spontaneous demonstrations in the streets of Buenos Aires and the inexplicable acts of repression by the Police were difficult to understand: “It was a moving fact that I saw in the distance”, recalls the scientist, whose place of work is the Bariloche Atomic Center. Ten years later, when the trial over what happened on those days –in which five people died and hundreds were injured- began, Pregliasco was summoned by the Justice to analyze everything because of his experience in the field of forensic physics. The Federal Court Number 6 summoned him to lead the graphic reconstruction of the events.

Pregliasco had already participated as an expert in other important cases: he developed a system to reconstruct the scene that managed to determine the origin of the eight shots that killed Teresa Rodriguez, who was murdered during the eviction of a picket line in Neuquén, in 1997. He had also been part of the team that identified the name of Miguel Bru, a university student from the city of La Plata who has been missing since 1993, in the book of the 9th police station where he was arrested. Besides, he had carried out the emblematic reconstruction of the Trelew Massacre of 1972. “What one is doing gives you ideas to make the expert reports that come later,” he says. But the events of December 19 and 20 had a peculiarity: the amount of evidence, the volume of information was terrible.”

There were one hundred and twenty-six videos in VHS, which is more than sixty hours of recording –between official footage and others from open television channels- that recorded what had happened in different locations: Plaza de Mayo, the Obelisck, the Congress, Avenida de Mayo, and Diagonal Norte. The videos had remained, until then, stored in boxes in two different courts. There were also hundreds of photographs and their negatives. Digital cameras did not exist yet with the recording of the events made by different photojournalists.

There was no time to lose: it was necessary to begin to classify, curate and organize this material as soon as possible so that it would help in the resolution of the trial. “At that time, the president of CONICET, Roberto Salvarezza, ordered an advance of funds for materials with which we bought two computers and two large monitors that we installed in an office in Bariloche,” said Pregliasco. Then, that money was returned by the Court that asked us for the expert testimony. But thanks to that management of that president of the Council, we started to work the day after we were called.”

The evidence

How to organize the task? That was the initial question they had to solve. With Lucas Micheleti, one of his students he selected to be part of the of team, the first task was to declassify the images transmitted by Channel 4: in 2001, the Secretary of Internal Security of the government of Fernando de la Rúa, Enrique Mathov, and the head of the Argentine Federal Police (PFA), Rubén Santos, had ordered and directed the police repression in the streets while they observed these images from a console. Both were now charged in the case. These videos were especially important, but there was a problem: they weren’t all the cameras all the time, but the cameras of the moments that interested them. And we had to reconstruct what had happened the rest of the time.”

To fill in the missing parts, they searched for videos from television channels that had broadcast live that day. “There were for or five channels that during their usual programming –gossip programs, cartoons –interrupted every so often and showed some of the locations where the events of that day occurred. Some videos had the time set in the corner, which made it easier for us to put them in order,” Pregliasco explains.

They systematized all these videos, reporting the area, the time and looking for synchrony: “Since we had different video sources, we looked for coincidences between the images on Channel 4 and those on television. When we captured the same movement with the two cameras, which could be from the legs of a horse or people on the street, we could synchronize one camera with the other” says the physicist.

Once the images were synchronized, we had to design a computer program that would allow them to see all the images simultaneously, something that with the technology available at the time was a challenge. They managed to do it and called it “The panopticon.” After indicating a time slot and location, this program searched for video material or relevant videos. The program would then open all matching materials on small screens simultaneously. “We made a kind of video surveillance panel of the day to place images in time and space: it was the visual memory of December 20 at all times.” They still had to add to the Panopticon photos of different photographers who had recorded the events that day. To locate them in time and space, they worked with the negatives. Once all the material was gather, there was only one thing left: building relationships.

“We managed to develop about five hundred relationships”, says Pregliasco. To enter them into the computer we established that each relationship that entered into the system restricted the time possibilities. That was how we located a lot of bits of material in an hour. It was important to place them on time because there is an effect that is like this: what is filmed, is filmed because something happens. What is filmed in a repression is a pure act of violence. The moments when nothing happens, nobody films, but we wanted to rebuild everything: the moments of tension and those of calm. Knowing the moments of tense calm, and others where everything happened very quickly, helped us to locate the people who were in the square in space and time so that later those responsible could be pointed out.”

A month and a half later, the one hundred and twenty-six hours of VHS that had been stored in two courts became hard drive that contained all the evidence sorted, preserved and classified. When the team of experts delivered it to the court, each of the parties involved had it at their disposal. But that was only the beginning: there was still an arduous task ahead.

The story

The second part of the expert testimony consisted of developing a narrative about the video: a detailed description of the images already ordered was needed. It seemed to be simple, but it became a real challenge: “There I discovered that it was a very big change: writing what was happening in the video. It was an interesting task because describing it improved our perception about what we saw, but we did not know what words to use because they were loaded with interpretation,” explains the scientist.

How to call the people who appeared in the videos: “demonstrators”, “passers-by”, “political activists”, “the people”? How is it possible to describe the actions of the police: “the police advanced” towards the protesters, “charged” towards them, and repressed them”?  Each word denoted an intention. The words had to be as faithful as possible to what they saw, being aware that achieving a certain neutrality in language is a utopia.

“When we made the description of the videos, the significant actions of the day naturally appeared by theme and time coordinates,” Pregliasco recalls. In this way, the story of the events was well structured, in chapters: in the morning there were evictions, at such a time such a thing happened, with so many people. That was a great advance: we went from the collective and visual memory of what was a day of rage to seeing the changes in the behavior of the police forces and of the people throughout that day.”

The VHS boxes had already been converted into a hard disk, and the hard disk, a year after the expert testimony began was transformed into two documents, each more than fifty pages long, with the narration of everything that happened on December 19 and 20. “That work was called ‘atomic transcription’ and it was our great contribution. Based on our work, the Justice made its decisions,” explains the researcher.

Some years after completing their task, Pregliasco and Micheletti were summoned to testify as experts in the oral trial conducted by the Federal Oral Court Number 6. The physicists attended the trial for two days: they spoke for more than five hours each. They brought their computers, recounted the entire process they had gone through to obtain the expert testimony and answered questions from the parties. “It was very stressful, a situation with a lot of exposure,” Pregliasco recalls. At the end of the trial, Mathov was sentenced to four years and three months in prison and Santos was sentenced to three years and six months in prison and there were lesser sentences for seven other police officers.

“Although the expert testimony did provide great discoveries –we did not identify a responsible person–, we were able to describe the entire day, with the moment of detainees, for example. And the final result was a diagram with everything that happened: we placed the time on the X axis and the vertical the space, Plaza de Mayo, Avenida de Mayo, 9 de Julio, Obelisco, Diagonal Norte. Structuring things in time and space was very difficult, articulating and putting the disorganized information in a way that some else could use was the most complicated task. That final diagram was the synthesis of all our work,” says Pregliasco.

Over time

Twenty years after the events that occurred on December 19 and 20, Pregliasco reflects: “If something similar happened again today, or we had a similar task, we would have thousands of videos and photos thanks to cell phones. Knowing the time and place would be easier and could be reconstructed better. And thanks to technology we could have better software to solve it.

This expert testimony has taught us a lot. “I’ve learnt to look at the images with a different vision: it educated my eye to see what is important from an expert point of view and what is not. When a policeman hits someone with a stick, you are shocked by the fact that you don’t look at what is happening behind the scenes, how many stones are on the floor, if there is a watch on the scene. And that gives you fundamental clues. You have to learn to disarm the narrative of the image to see other things. I also found out that writing it down helps you see well,” the scientist comments.

Pregliasco compares the expert testimony, as physicists, with the most famous tool in the universe of particle physics: the Large Hadron Collider, built in 2010 by the European Organization for Nuclear Research (CERN).  It is a machinery that accelerates particles, stationed in a Laboratory in Geneva to analyze the by-products of particle collisions to be analyzed: through this tool, scientists try to unveil the structure of the subatomic world and the laws of nature that rule it. “The type of reconstruction that we did in this expert report is similar to it because it has a lot of detectors of events in different moments and it is necessary to apply a methodology to try to reconstruct what happened graphically, represent the events, locate the facts over time, understand the structure of the data. What we did was the same, but it was more difficult because the detectors, which were the cameras, only detect a lot of things,” he explained.

The expert testimony of December 19 and 20 is one of the most emotional works of Pregliasco’s career due to the historical dimension of the events and the impressive images. “We had to be patient, take lots of breaks. It was a very moving task. What helped me was to try to objectify it, to appeal to scientific thought, to organize things and make a human contribution from science. After all, we didn’t want to do just a reconstruction for the trial: we wanted to reconstruct that day, from which we are still experiencing some consequences, which was so important for Argentina and that in some way reconfigured the political map. Today, that day, is still important,” concludes the scientist.