The case of Yara Gambirasiokilled at 13 on the evening of November 26, 2010 in Brembate di Sopra (Bergamo), was one of the great crimes in recent Italian history, but not everyone knows that it has been resolved thanks to a large scale employment of the science. In fact, the scoring of the life imprisonment of Massimo Bossetti For the murder of Yara came after a carpet investigation that saw about 20,000 DNA tests in the province of Bergamo: it was the larger genetic screening ever made in Italy. The outcome of the investigations was the result of a huge number of comparisons between the DNA Found on the victim’s briefs and the genetic profiles of the local population.
Investigations on the DNA found on Yara’s body: genetic screening has been held
“Unknown 1“It is the appellation given to the male genetic profile (obtained fully) extrapolated from sample 31taken from briefs by Yara Gambirasio, whose discovery was communicated by the Ris in May 2011 and deemed useful for future comparisons. The investigators immediately considered the DNA of unknown 1 should Being that of Yara Gambirasio’s murderer: otherwise he could not explain his presence on the girl’s briefs.
To try to identify the identity of unknown 1, several lists of subjects were therefore created, based on certain criteria In order to withdraw DNA samples from compare with the unknown profile, including users of mobile phones who hooked themselves to cell Of the area of the find and the gym where Yara had been seen for the last time, the visitors of the gym itself and the 31,000 members of the disco “Le Sabbie Mobili” of Chignolo D’Isola, not far from the place of finding the corpse.
After about 2000 negative comparisons In July 2011 a turning point came: correlations were found between the DNA of unknown 1 and the one taken from the salivary swab of Damiano Guerinoniresiding in Brembate above and a member of the “Le Sabbie” disco, who, however, at the time of the disappearance of Yara, was in Peru.
The scientific police therefore focused on the analysis of thechromosome aplotype ya marker commonly used for i paternity test which is handed down in an alternating way of generation to generation. Given the unchanged transmission of this feature of father from father to son, the investigators tried to reconstruct the genealogical tree of Damiano Guerinoni, taking salivary champions from all living male descendants.
As we came to Massimo Bossetti in the case of the murder of Yara Gambirasio
This investigation led to the profile of Pierpaolo Guerinonison of Giuseppe Benedetto Guerinoni (deceased in 1999) whose nuclear DNA was almost identical to that of unknown 1, differing only for a marker (TH01), a small region of DNA present on the Y chromosome. Pierpaolo’s DNA did not coincide with that of unknown 1, but that of Joseph suggested that the latter was the father of unknown 1. From here the hypothesis that unknown 1 was a illegitimate child by Giuseppe Guerinoni.
To be sure, the corpse of Giuseppe Benedetto Guerinoni came reinformedand the comparison of his DNA with that of unknown 1 was in a percentage of paternity estimated at the 99,9999987%. In short, Giuseppe Guerinoni was the father of the murderer: now all that remains was to find the mother.
The investigators reconstructed the life of Giuseppe Benedetto, where he lived, where he worked and what places he attended. They were found 532 potential candidatesand through investigative investigations it came to Ester Arzuffiwhich according to rumors collected in the country would have had a secret relationship with Guerinoni in the 1960s. Esther had lived for about three years in the town of Guerinoni, Parre, and in May 1969 he moved to Brembate di Sopra.
Once sequenced nuclear DNA complete with Ester, it was seen that it was Exactly half the missing of the DNA of unknown 1. Ester had two legitimate children: Massimo Giuseppe And Fabio. Massimo was the main suspect given his date of birth (28/10/1970) He was closer to the transfer of the woman from Parre to Brembate.
Massimo Giuseppe Bossetti was stopped in 2014 with the excuse of carrying out an alcohol test and his saliva was taken from the mouthpiece of the stunning. The following analyzes revealed that the genetic profile corresponded perfectly to that of unknown 1.
The analysis techniques used to resolve the Yara case
The identification of Massimo Bossetti In the Gambirasio case it was possible thanks to the application of genetic analysis techniques, in particular through the analysis of polymorphisms Short Tandem Repeats (Str) on nuclear DNA, the one present in all the cells of our body that makes each individual unique.
The stri are Short repeated DNA sequences several times in a consecutive way. The variation in the number of these repetitions between individuals makes the strimorphic strips or useful for distinguishing one person from another in a unique way.
In the case of unknown 1, they have been identified 24 Strosomic Masserchiers (i.e. that reside in the non -sexual chromosomes), to which they have been added 12 chromosome markers X e 16 Chromosome Y markers, for a total of 52 markers. This number is considered “gigantic” in the forensic field: international standards usually provide for it 13while for forensic practice they consider it necessary 15-16. The vastness of the markers analyzed gives identification a probability of infinitesimal errorequal to 1 out of 20 billion.
The most advanced analysis techniques allow to amplify even very short DNA sequences (mini-stast) when the amount of sample is small, under the 100 picograms/microlitro. To give an example, the DNA present in the sample that allowed DNA isolation complete with unknown 1 were more than 2000 picograms/microlitroa quantity widely sufficient for analyzes. In addition, most of the analyzes on unknown DNA 1 have been repeated with the same kit or with different kits to increase the number of markers and the reliability of the tests.
