Chris_Halkides
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Mixed DNA is a common occurrence in forensics. Luminol detects the possibility of blood, nothing more. The negative TMB tests means that it probably was not blood, and the lack of a confirmatory test means that no one has any business concluding that it was blood. The lack of good forensic technique might have led to apparently mixed samples of DNA in some instances. It is known that gloves themselves can test positive for DNA, yet Stefanoni only indicated that they were changed after handling an item that was particularly soiled (as summarized in Massei). The lack of substrate controls (DNA tests near the luminol stain) is another strike against the stain as evidence. One of the samples from Filomena's room had some extra alleles (possibly Rep. 177). The forensic police did not obtain Laura's or Filomena's reference profiles; therefore, unidentified DNA might be theirs for all anyone knows.Not to mention there was a mixed DNA sample of Meredith and amanda in Filomenas room. The excuse they lived together can't be used for this one. Considering there was no sample of either other roommate mixed with Meredith. Not even Filomenas own room.
How did that mixed sample revealed with luminal get there?
Yet first among equals in what is wrong with this evidence is the fact that it was collected on 18 December. The American Bar Associations standards for collecting evidence reads in part, Standard 2.1 Collecting DNA evidence from a crime scene or other location
(a) Whenever a serious crime appears to have been committed and there is reason to believe that DNA evidence relevant to the crime may be present at the crime scene or other location, that evidence should be collected promptly.
I would either exclude all evidence taken on this date or I would take it at a deep discount to evidence collected promptly, and that goes for evidence collected against Guede as well. There was traffic in the cottage in the intervening period; Barbie Nadeau took a picture of an open door behind some crime scene tape on or about 14 November, for example.