In the last post I showed how the existing DNA profile from the car sample could be used along with DNA profiles from McCann family & friends + a others to enhance our understanding of who might have contributed to the DNA profile and thus how likely it is that Maddy was one of those people.
Now I would like to consider what else should have been done in 2007 as soon as the DNA profile was known.
The whole of the carpet from the car boot should have been retained and sealed as evidence. It should have been cut into many (at least 100) small pieces in a grid like fashion ad each piece subjected to DNA extraction and LCN DNA analysis.
In addition random samples should have been taken from all interior areas of the car, seats, carpets, swabs from door handles, windows, floor (e.g.under car boot carpet) etc. Perhaps a further 100 samples. These should also have been subjected to LCN DNA analysis.
What would this sampling & testing reveal?
Had this been done several things might have been revealed including:-
1. Was it possible to get DNA profiles from any other parts of the vehicle?
2. Were the 15 (or more or less) Maddy markers present anywhere else in the vehicle?
3. Were there parts of the vehicle that gave single person DNA profiles? (I am aware of the Gerry McCann profile from the key fob I'm talking about the car itself.
4. Were the 15 Maddy markers present in other pieces of carpet from the boot?
5. Were the 22 other markers from the car boot present in any other samples?
6. Were there samples that included markers not found among the 37 in the car boot sample?
7. Was there an area of the car boot carpet that gave significantly poor or zero DNA results?
What might any or these results indicate or prove?
1. If yes then these profiles might be used to show how the 15 Maddy markers could have come together in the single sample from the boot.
2. If yes then the pattern of profiles seen would show whether the 15 Maddy markers were present in only one or a few areas of the car or were widespread. If they were present only in one area that would indicate her body could have been placed in the boot at some point. If widespread the chances are that these markers are coming from the DNA of others.
3. Any single person profiles would identify people who had definitely been in the vehicle (or their DNA transferred there. Clearly a single person profile that matched Maddy's would be significant, but others could also be used in a subtraction analysis on other samples.
4. If yes this would identify an area (or areas) that had Maddy's markers. The size and shape of any such areas would be very informative. e.g. a few drips spread out, a single small area consistent with a pool of liquid soaking into the carpet, a ring with a blank area in the center consistent with cleaning of a spill or leak etc
5. The presence of these other 22 markers in other samples, especially any single ID samples would permit subtraction analysis on the boot sample
6. This would show whether the car boot sample contained all the markers present in the car or not. Creating a complete picture of the amount of DNA contamination in the car.
7. This would indicate an area that had been specifically cleaned shortly before the car was seized as evidence.
Why weren't these things done?
I am at a complete loss to explain why these things or at least some of them were not done. The case was huge worldwide news at the time. The McCann's were being suspected of disposing of Maddy's body. The evidence from the single sample in the car boot suggested that could be the case but was inconclusive. Here was a great opportunity to either clear the McCann's or gather evidence that would help to prove they did dispose of Maddy's body. Why did no one.... NOT EVEN THE McCANN's themselves..... insist that this car was examined thoroughly and every scrap of evidence extracted?