If one were looking for an example of laboratory malpractice, the following account of the contradictory information forensic worker P. Stefanoni wrote in her report (RTIGF) and testified to compared to what she indicated in her written lab record (SAL) is a good example:
It is no wonder, then, that forensic worker P. Stefanoni declined to provide a copy of the raw DNA data including the results for positive and negative controls to the court or to the defense. That raw DNA data, which could not be readily falsified by hand, would have been revealing of actual levels of contamination and many other interesting details of the laboratory effort.
Source of quote: https://knoxdnareport.wordpress.com...egarding-item-36-knife/quantification-of-dna/
From this, it can be inferred that what is reported on page 78 of the RTIGF (and confirmed in the GUP questioning, page 178, where it is claimed that quantification was performed using Real Time and that quantification of the Y [chromosome] was not carried out) is not consistent with what was performed in reality. In fact, the tables show that quantification of the DNA extracted from all the samples taken from Exhibit 36 was carried out using the 770 Sequence Detector ABI PRISM™ equipment (Applied Biosystems); in contrast, it is apparent from the attached cards that the aforementioned method was only performed on samples D-E-F-G. A different method was employed for samples A-B-C using the Qubit Fluorometer™, and not mentioned in the final Technical Report, as would have been due and correct.
Regarding the interpretation of the quantification, it should be noted that on page 78, the following is stated: “the samples testing positive to quantification (samples A and B) were subjected to amplification and subsequent capillary electrophoresis…”.
As regards the quantification of sample A (knife handle) the results obtained with the Qubit Fluorimeter™ show that the concentration of DNA in this sample was equal to 0.08 ng/μl. Taking into account that the “quantity of extract” was 50 μl (c.f. SAL), and multiplying 0.08 ng/μl x 50 μl, the total [amount] of DNA was equal to 4 ng: certainly a significant quantity, which allowed sample A to be considered positive to quantification.
On the other hand, it is not possible to comprehend the criteria adopted in the assessment of the positive quantification result for sample B and the negative result for sample C, given that the same result, “too low”, was obtained for both samples: that is, a value which must be considered not only below the sensitivity threshold of the Fluorimeter indicated by the manual (DNA concentrations equal to 0.2 ng/μl), but below 0.08 ng/μl, a value which the Fluorimeter detected for sample A.
Nor is it comprehensible, considering the negative results on sample B, what Dr. Stefanoni reported during the GUP questioning (page 178) where she stated that the DNA in sample B, quantified with Real Time PCR (it is recalled that such quantification as confirmed during the hearing was never carried out or, at least, no documentation was provided to support this claim), was “in the order of some hundreds of picograms”, a value which does not appear in any of the documents provided to us (SAL, Fluorimeter report, Real Time report, RTIGF).
It is no wonder, then, that forensic worker P. Stefanoni declined to provide a copy of the raw DNA data including the results for positive and negative controls to the court or to the defense. That raw DNA data, which could not be readily falsified by hand, would have been revealing of actual levels of contamination and many other interesting details of the laboratory effort.
Source of quote: https://knoxdnareport.wordpress.com...egarding-item-36-knife/quantification-of-dna/
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