"The Minister of the Interior, as well as the Prime Minister, use professional jargon, which can be understood in interpersonal communication within the laboratory, but neither Stefanović nor Vučić understand it, just as neither do the public they address," he told " Time" professor Oliver Stojković, head of the DNA laboratory of the Institute of Forensic Medicine in Belgrade, and adds: "When he said 'partial DNA trace', Minister Stefanović probably meant a partial DNA profile. A complete DNA profile contains data on about fifteen genes that are usually analyzed in this type of expertise, while a partial or "partial" DNA profile has data on a smaller number of genes. Such partial DNA profiles are obtained by analyzing scarce biological traces, which are damaged by the passage of time and with which there is less certainty in the identification of the person from whom the DNA originates. Let's say, if you read my partial signature "ol.v.rst.jk.vić" somewhere, you will be able to identify me more easily than if you find only "o…..s…….ć".
"WEATHER": How much it complicates the investigation if there are traces "found through each other" as stated by Minister Nebojsa Stefanović?
OLIVER STOJKOVIĆ: In the specific case, it is obviously biological traces that are not only scarce and damaged, and therefore "partial", but also mixed. We call mixed biological traces found in the same place, which come from more than one person. Samples for DNA analysis are taken by removing, wiping, a biological trace from a small surface, for example the size of a metal coin, with a wet piece of cotton wool. In this case, genes from at least three individuals were found in one sample.
Imagine you found:
In some places you have three letters and you conclude that the names of three people are written there. So the trail is mixed. Some letters are missing, so the trace is partial. But can you reliably claim that you "read" the names of your interlocutor (Oliver Stojković), our Prime Minister (Aleksandar Vučić) and your journalist and reporter (Dragan Todorović)?
Stefanovic also stated "that the police will try to obtain a sample for comparison by other methods and then try to compare it with the partial traces of DNA found on the weapon". What other methods can be involved?
I'm really not an expert on police methods, and even less on what a minister might mean if he says something. Such DNA profiles, which are both mixed and partial, are not acceptable for comparison with databases. It is possible for the police to suspect someone based on other information, and to directly compare that person's DNA profile with the traces. Second, in this particular case, we are talking about a large number of objects, so it is possible that samples were not taken from all objects and from all places (rocket launchers are not very small objects). In one murder case in Germany, the DNA laboratory there isolated 600 biological traces from just one sweater. It should be borne in mind that these methods are not cheap at all - isolating one biological trace costs around 100 euros. Our prosecutor's office is usually not able to allocate such funds for DNA analysis, so in our practice biological traces are removed from two or three places. And thirdly, it is possible for the police to turn to a laboratory that has more sensitive equipment, to obtain a more "complete" DNA profile. For example, the DNA laboratory of the BIA has a more modern apparatus for DNA analysis than the MUP's DNA laboratory.
According to your experience, what kind of DNA traces could have been left by the perpetrators who took weapons and ammunition to Jajinci and how long could these biological traces have remained and still be usable for DNA analysis?
Weapons and ammunition, as reported in the media, were found in crates, where various biological traces could have remained preserved from the effects of the environment for a long period of time (days, weeks, months or years). A few years ago, in my laboratory at the Faculty of Medicine, a biological trace was found on the optical sight of a rifle found along with some other weapons and ammunition in a soldier's bag found on the side of the road, the analysis of which resulted in a complete DNA profile suitable for identification and comparison with databases . A fortunate circumstance in that case was the fact that the weapon was fired by bringing the weapon close to the face, so traces of saliva could be found on the rifle, which are much more suitable for DNA analysis than traces originating from the skin. For example, when you touch something, you leave 1000 times less biological material than there is in a drop of your blood.
