Knox Appeal: Experts on Key DNA Evidence File Their Report

On 29 June 2011, The two court-appointed forensic experts—Carla Vecchiotti and Stefano Conti (pictured above), both from the Legal Medicine Institute of Rome’s La Sapienza University—in the Amanda Knox and Raffaele Sollecito appeals trial filed their report to a tribunal in Perugia (Report translated HERE). Both experts were appointed to analyze two pieces of physical evidence being contested by the defense: the knife (Item 36) and the bra clasp (Item 165B).

The experts were not able to retest the DNA on the bra clasp and the knife because there was not enough DNA to retest. So, they were then assigned to judge “the degree of reliability of the tests carried out by the forensic police on the evidence based on court documents, specifically with reference to any possible contamination.”

During the first trial, experts for the prosecution determined that a small sample of Kercher’s DNA was found on the blade of the knife and Knox’s DNA was found on the handle. Also during the first trial, experts for the prosecution—and even Professor Francesco Vinci, initially retained by Sollecito’s legal team—said that the bra clasp showed traces of Sollecito’s DNA.

In the 145-page report filed in late June, the court-appointed experts concluded that while Knox’s DNA was on the handle of the knife, the tests on the blade were “not reliable” because the correct international protocol for tests on small samples, called low copy number (LCN) DNA analysis, had not been followed. The results were therefore inconclusive, according to the experts. The experts also said that both the knife and the bra clasp had been collected and handled without following international procedures. They did not, however, explain what international protocols were not followed by Dr. Stefanoni and her staff.


In regard to Kercher’s DNA being found on the blade of the knife, the report concludes by saying, “It cannot be ruled out that the result obtained from sample B (blade of knife) derives from contamination in some phase of the collection and/or handling and/or analyses performed.” The experts, however, did not expound on, or even give any specifics on, this assertion. There was not a theory posed as to how contamination could have occurred; there was no theory posed on the likely possibility that contamination occurred (i.e. to what degree possible contamination occurred).

So, if it cannot be ruled out that contamination may have occurred; it is also safe to assume that it cannot be ruled out that contamination didn’t occur. Therefore, we appear to be right back where we started from. When first approached by police and informed that Meredith’s blood was found on the blade of the knife, Raffaele Sollecito confirmed this, claiming that he had pricked her with the knife accidentally while cooking a fish dinner for her in his apartment. It was later confirmed that Meredith had never been to Sollecito’s apartment. If we cannot trust certain scientific processes, can we at least trust common sense? Good detective work still remains the staple of any effective investigation, doesn’t it?

Yet, clearly the hardest evidence of the two to try and hold as unreliable is the bra clasp. According to Dr. Stefanoni’s report, the clasp contained 1.4 nanogram (or 1400 picograms— approximately 200 cells) from Sollecito, plenty to conduct a reliable test (the minimum for reliability using the PCR Process is typically 1 nanogram).

By claiming “possible” contamination on this item, all are confirming that it is indeed Sollecito’s DNA on the clasp, and that it got there by improper collection methods. All they are saying is that his DNA, which was positively found on the bra clasp, could have been deposited there, by forensic experts on the scene, from somewhere else within the cottage. Yes, the bra clasp was not collected until 18 December 2007.

But forensic video of all inspections show that the clap never left Meredith’s room. So, if Sollecito’s DNA was taken from an area of the cottage (crime scene) and deposited on the bra clasp at some point, which is what this contamination analysis means, then where did it come from?


In judge Massei’s report (pg. 268) he explains that a “cigarette stub” was the only other place that Sollecito’s DNA was found in the cottage. Moreover, judge Massei explains the impossibility of such a transfer (on page 274 & 275). In his report, Massei explains how the search method was conducted in Meredith’s room, which consisted of “subdividing the areas: in Meredith’s room no other object apart from the hooks [of the bra clasp] was shown to carry Raffaele Sollecito’s DNA; Raffaele Sollecito did not leave his DNA on any object that was in Meredith's room; and more importantly, none of the operators, after having touched some object which might have had Raffaele Sollecito’s DNA on it, then touched the hooks of the small piece of bra so as to make even hypothetically possible a transfer of DNA (from the object containing Sollecito's DNA to the gloves, from the gloves to the hooks).”

Remember, it is very likely that Vecchiotti and Conti do not know this. They were not appointed to be experts on the entire case and read all of the evidence; they were hired for a specific reason: to evaluate two pieces of physical evidence. Judges and members of the jury will surely take this into account. They will get the full scope of the evidence and weigh it all against one another.

In regard to the report, Kercher family lawyer, Francesco Maresca, said, “the word of the independent experts would not be the last word, and said he would raise his objections during the last week in July, when the report will be formally discussed during a week of hearings.” Maresca also asserted that the scientific police and the consultants, whose results the independent experts are reviewing, have “far more experience” than the independent experts. “I was surprised that these experts were so certain, and gave such strong, drastic opinions, given that they don’t have the same number of years of experience under their belt,” Mr. Maresca said.

The next hearing in the case is scheduled for 25 July 2011, where these independent experts will formally discuss their results and the prosecution will certainly provide a counter argument.