Komplex DNA-Evidenz

cwporter schrieb:In Apartment 5A, the apartment the McCanns rented for the week, Eddie, the 'cadaver dog' and Keela, the 'blood-hound’, both clearly - and independently from each other - marked precisely the same location, behind the sofa in the living room (which had been moved by the McCanns from its original location). The tiles where Keela scented the blood were carefully removed, first analysed by a Portuguese laboratory, and then sent to FSS. The blood found by Keela was by then degraded, quite probably, it was said, due to cleaning agents having been used to clean the area where the dogs detected the corpse scent and the blood.

As a result, the FSS lab was able to check only 5 markers from that site. Each one of those 5 markers matched Madeleine's DNA. Or, to re-phrase this a different way, there were no markers that could not have come from Madeleine, so the idea that it was her blood could most certainly not be ruled out.

Far more conclusive evidence was found in the Renault Scenic, registration no. 59-DA-27 - the car hired by the McCanns. Eddie, the 'cadaver dog', and Keela, the 'blood-hound’, both clearly marked the same car and the same location within the car. The blood found there by Keela (beneath the carpeting in the well of the car) was also degraded. But the FSS lab was able this time, on its first analysis, to find 19 markers, of which 15 markers matched Madeleine's DNA - again, meaning that there were no markers within these 15 that could not have come from Madeleine. With 15 markers out of 19 all matching Madeleine’s DNA, that would give analysts 99.9% confidence that the blood samples were from Madeleine. The DNA of the degraded blood was found not to match with the DNA of the twins, Sean and Amelie, a further indication that the blood was Madeleine’s. These were the initial results that the FSS initially communicated to senior investigating officer Goncalo Amaral and his team.

The law differs from country to country as to how many out of an individual’s 19 or 20 DNA ‘markers’ are needed by the courts to prove that any DNA sample comes from that individual. Many countries accept 15 markers out of 19 as sufficient proof. Under Portuguese law, however, the courts require all 19 markers to be confirmed. This was what is called ‘Low Copy Number’ DNA and so all 19 markers could not be obtained.

We might add here that when the British police cross-check the DNA of a suspect with its database (said to consist of 2.5 million people) of people who have been arrested on suspicion of a crime, they use only 10 markers out of 19 in order to establish a DNA ‘match’.

The scientist who invented DNA fingerprinting two decades ago, Professor Sir Alec Jeffreys, said however that using 10 markers to obtain a sufficiently reliable ‘match’ was insufficient proof. He went on to state that 15 markers would provide sufficient evidence to be conclusive. He said: “The current DNA database uses 10 distinct markers to obtain a match and this means there is still a residual risk of a false match. They should use about 15 markers; 15 markers would close the possibility that the match from a crime scene sample is genuine but a fluke”.

To find 15 out of Madeleine’s 19 markers present means that the chances that the traces of blood in the hired car came from anyone other than Madeleine were fewer than only 1 in 1,000.

The key point to be made is this. These initial FSS results, on their own, showed a better than 99.9% chance that the blood in the McCanns’ hired car was Madeleine’s. For some experts, and under Portuguese law, 15 markers out of 19 - bearing in mind the high level of proof required in a criminal trial - stops just short of providing absolute proof that the blood is that person’s. But we must take these strongly indicative results (with all 5 markers in one sample and 15 in another that could not have come from Madeleine) together with all the other evidence in this case. We can surely say with confidence that the chance of those 15 markers belonging to someone other than Madeleine is next-to-nothing, especially when we take into account other significant forensic and circumstantial evidence. These initial DNA results, then, amount to more evidence in the case pointing very strongly in the direction of Madeleine being dead in her holiday apartment on 3rd May 2007, the day she ‘disappeared’, and then her body being transported in the Renault Scenic at least three weeks later.

In a case reported in October this year, a killer was convicted thanks to relative's DNA. The Forensic Science Service and police used ‘familial searching’ to uncover a close relative of Craig Harman, from Surrey, who had a criminal conviction and was on the DNA database. The relative's profile matched the DNA on the brick by 16 out of 20 points. This led police to Harman, whose DNA gave a perfect match. He eventually confessed to the drunken act of violence.

It must be said, however, that this first analysis, given to the Portuguese and Leicestershire detectives in June, was overridden a month later when the FSS issued a more detailed report. By now, as the former senior investigating officer Goncalo Amaral confirms in his book, political interference in the case had begun, with successful attempts being made to get the FSS to water down their initial conclusions. By July, the initial samples had been re-tested and were now found to contain 37 markers, or ‘alleles’, not just the original 19. The sample appeared to have been contaminated by staff of the FSS laboratory. Though there were now reported to be 37 ‘markers’, there were still, of course, 15 that were a match to Madeleine’s DNA. That fact that the FSS appear to have contaminated the sample does not negate the match. It simply makes it somewhat less certain that the blood was Madeleine’s.

By the time they issued their more detailed report, the FSS said that they were only able to confirm that the results of the analysis were ‘indicative’ that the blood found was Madeleine’s. They later added that the results were ‘too complex for meaningful analysis’. We need to bear in mind that whilst the Portuguese police have released some FSS analyses and statements, they have not yet released others to the public, including the reports of their first tests, which gave the strongest indications that the blood was Madeleine’s. The leading Portuguese detective on the case is clear that intense political pressure was successfully brought on the FSS to modify its earlier results, whilst the leading British detective on the case, Stuart Prior, was overheard to be ‘furious’ with the FSS when he learnt of their watered-down opinion. It seems he also believed that there had been political interference to secure a less conclusive result.

summacum schrieb:Nun, das ist dann aber schon mehr als ein soft fact - das wußte ich bis dato nicht. Dafür werden andere schon verknackt...