The murder of Yara Gambirasio
Yara Gambirasio was a 13 years old girl of Brembate, a small town in the province of Bergamo, in Northern Italy, who disappeared on November 26, 2010, and whose corpse was found in an open field in the nearby Chignolo three months later, on February 26, 2011.
The murder triggered one of the most imposing and expensive investigations in Italian history: the rumor has it that it could have been cost to the Italian taxpayers as much as 8 million euro.
The numbers are certainly impressive: up to 27500 DNA samples collected in the area, a similar number of phones put under control and as much as 56 million conversations tapped, if media sources are reliable.
This gargantuan effort led, on June 16, 2014, to the arrest of Massimo Giuseppe Bossetti, a 44 years old (at the time) construction worker living at Mapello, another small town close to Brembate.
The Italian Minister of Internal Affairs, Angelino Alfano, announced the arrest on Twitter, saying that the murderer of Yara had been finally apprehended.
It looked like a slam dunk case, since it had been known for years to the public opinion that the DNA of the alleged killer (at the time named “Ignoto1”, that is “Unsub1”) had been found on the victim’s corpse and all the massive investigation was finalized to give a name to the owner of that DNA.
The prosecution and the media (or the prosecution through the media, if you prefer) announced soon after the arrest that Bossetti’s DNA matched the sample attributed to Unsub1 on 21 markers, forensically speaking an almost unprecedented feat and a watertight identification.
In the first weeks, indeed months, after the arrest I think few doubted that the case was closed and the trial just a formality.
The general expectation was that of a confession in face of such foolproof evidence of guilt, and perhaps some started to have doubts when this confession did not came after a few days or weeks.
Some started perhaps to reckon that not everything had to be taken for granted when the prosecution, after having first announced that they were going to ask for an immediate trial, extended the duration of the investigative phase and delayed the formal indictment.
To be honest, those in some way accustomed with Italian judicial realities started to see something else, something already seen multiple times before.
With such an apparently overwhelming and unassailable evidence at hand, the prosecution was nevertheless going on trying to pile up elements of circumstantial evidence that appeared more and more debatable, when not outright laughable.
Among the debatable are fibers found on Yara’s corpse and deemed “compatible” with the fibers of the seats of Bossetti’s light truck (as well as with tens of thousands of similar trucks and buses), or the alleged CCTV shots showing (apparently) that same truck “circling around” the gym where Yara was last seen alive at the time of her disappearance. Since no license plate was identifiable, the identification was based on the comparison of daytime photos of Bossetti’s truck with the rather grainy shots from CCTV taken with scant artificial light.
The phone cell records are also inconclusive and by now even pro-guilt people agree that they just do not give Bossetti an alibi.
Among the outright laughable ranks the alleged period of “lack of communication” between Bossetti and his wife around the day of the murder, deduced by the examination of the phone records, as if a possible marital crisis should lead someone to kidnap and kill a 13 years old girl, instead of searching for a more mature lover.
In the same league rank also unlikely witnesses testifying that they had seen a girl who could have been Yara sitting with a man who could have been Bossetti in a car that could have been Bossetti’s (this one even testified at the first grade trial), or that they had seen someone looking like Bossetti and sporting the unavoidable “icicle eyes”, loitering around Yara’s grave.
The latter, at least, was belied by the investigators themselves, who had placed hidden cameras near Yara’s grave years before.
Why going on assembling (and “leaking out” to the media) such an heap of debatable at best evidence, when allegedly there was that incredibly strong DNA evidence?
And at this point some, also on the Internet and the social media, have started to look more skeptically at the “queen evidence”, namely the famed 21 markers matching DNA.
Too good to be true?
The crucial piece of DNA evidence in this case is a trace named 31G20, collected on the victim’s panties.
In various court documents and expert reports it has been defined as of being of “outstandingly good quality” and “with abundant presence of cells”.
It matches with the defendant’s DNA profile on 21 markers or even more (numbers were flying around at trial): all those used in the CODIS plus others used in Europe.
Nevertheless, already back in 2012, the RIS (the special department of the Italian Carabinieri devoted to forensic investigations) pointed out that:
“Come stigmatizzato in più occasioni, lo studio analitico dei reperti oggetto della presente indagine è stato reso particolarmente difficile dal cattivo stato di conservazione degli stessi e dalla oggettiva complessità dei susseguenti esiti di laboratorio, non sempre ben interpretabili in ragione dell’elevato livello di degradazione biologica delle tracce presenti … […] … di contro, pare quantomeno discutibile come ad una eventuale degradazione proteica della traccia non sia corrisposta una analoga degradazione del DNA.“
“As it has been repeatedly stigmatized, the analytical study of the samples considered in the present investigation has been made particularly difficult by their bad state of conservation and by the objective complexity of the subsequent lab results, not always well construable because of the high level of biological degradation of the samples … […] on the other hand, it appears at least debatable how a possible degradation of the proteins in the trace isn’t matched by a correspondent degradation of DNA.”
What does this mean?
It means that the RIS were unable to positively determine the biological source of the trace (i.e. blood, semen, saliva, etc.), because (this is a subsequent deduction) they were unable to find the corresponding mRNA (messenger RNA) markers in the trace or proteins allowing it to be positively (and not just presumptively) identified.
What the RIS are puzzled about is that, if the trace is of so high quality as to allow such a good nuclear DNA profile, why does it not allow to determine its source? The only thing the RIS were able to exclude was semen.
It is not the only “oddity” of said trace: the mitochondrial DNA of the defendant does not show up in the trace either.
DNA can be divided in two types: nuclear DNA (or nDNA), that is the DNA contained in the cell’s nucleus and whose content is inherited half by the father and half by the mother of any individual; there is then mitochondrial DNA (or mtDNA), contained in the mitochondria of the cell (usually defined as the cell’s powerhouses) and that is inherited only by one’s own mother (who, in turn, got it from her own mother, and so on).
While nDNA contains much more information than mtDNA and it is the only one unique to a specific individual (except for identical twins), mtDNA is generally considered the one more able to resist degradation.
While one can find studies disputing mtDNA’s higher resilience with respect to nDNA, it is in any case considered at least as much resistant to degradation as nDNA and there are recent studies asserting the same for mRNA.
Moreover another mtDNA, not belonging to the defendant, but rather sporting a relatively rare (in Europe) R0a haplogroup, was found in the same trace which gave the famed 21 markers nDNA profile, so it cannot be said that Bossetti’s mtDNA was not found because of the inferior level of mtDNA sequencing techniques with respect to nDNA ones, as was stated at trial by prosecution experts.
So a trace presenting a nDNA of “outstandingly good quality” together with a lack of mRNA and mtDNA is an outstandingly rare beast indeed.
And it is not all, because according to the prosecution’s case Yara’s body remained lying in open country for 90 days after her death, and studies quoted during the debate on the case in Italy seem to exclude the possibility of the persistence of any nDNA for such a long time in those conditions, let alone the possibility of retrieving a sample of “outstandingly good quality”. A persistence going from 15 to (a very best case of) 60 days is all that can be found in published papers.
So what explanation can be found for such an unusual phenomenon?
Let’s say that a certain “current of thought” in Italy surmises that that DNA is indeed a synthetic one.
Its main reference is a 2009 article by Dan Frumkin et al. of the Israel Police showing how DNA attributable to an individual can be fabricated in a lab.
While Frumkin describes also a procedure for fabricating a whole human genoma, the easiest method illustrated in the article relies on the same PCR machines used to amplify DNA samples in genetic investigations.
And those machines (or “kits”) only amplify specific parts of a human nDNA, known as Short Tandem Repeat or STR, of course the same ones used to attribute a given sample to a given individual during a crime investigation.
This would quite easily explain the absence of mtDNA and mRNA: they were not fabricated alongside the nDNA’s STR regions … which, in this scenario, would be the only thing the alleged Bossetti’s DNA would be made of.
However, if the sample constituted by trace 31G20 were still available, there would be tests outlined in the above-mentioned article by Frumkin that could reveal the synthetic nature of the DNA, if that is indeed the case of 31G20.
Once established that that DNA has been fabricated, questions about the why and who could perhaps be the object of another investigation, but Bossetti would be almost certainly acquitted, since the remaining evidence is well below the “beyond any reasonable doubt” level.
Moreover, if a critical piece of evidence could be positively proven as having been fabricated, shadows would be cast also on much of the remaining evidence, from fibers to CCTV shots.
But do they still have the possibility of doing any further test on trace 31G20?
Apparently originally very abundant, with a 1400 pg/microliter concentration for the male component, this trace has been exhausted through multiple test even before the trial, albeit it was absolutely clearly from the start that it would have been the pivot of the whole investigation and hence of the trial.
It is, however, possible that at least another trace (labeled G1-ext) may contain enough of Unsub1’s DNA (1000 pg/microliter) to allow such a test, provided it too has not “evaporated” in the meantime.
The case presents anomalies also outside of the genetic field, like the one concerning the state of conservation of the clothes on the corpse: close to pristine on the upper half of the body, particularly the jacket, and highly deteriorated on the lower half.
Moreover on the right cuff of the jacket there was found an “abundant” trace of a DNA attributed to Silvia Brena, at the time gym instructor of the victim, and who has always denied any physical contact with the victim that day. That DNA also presents many of the characteristics of the one attributed to Bossetti: great persistence in the open for long times and impossibility of determining the source.
So it could well be synthetic too, and of this trace there is enough surviving material to perform a methylation test, but so far everything has been done to keep it outside of trial.
Or like the lingering question of how hundreds of searchers, also helped by helicopters and cadaver dogs, were not able in three months to find Yara’s corpse not in a remote desertic area, but a few hundreds meters away from an industrial area and a discotheque and close to the town of Chignolo.