Knox Appeal: The Prosecution Strikes Back

Amanda Knox entered the courtroom today for the second day in a row. This time she was wearing olive green satin blouse and black slacks, and gave a smile to her father, stepfather, and best friend as she was led to her seat. Dr. Patrizia Stefanoni (above) took the stand again today to dispute the DNA results given by the two court appointed experts, Professors Carla Vecchiotti and Stefano Conti.

Yesterday Dr. Stefanoni was armed with 119 PowerPoint slides to explain her analysis. During her presentation some had a hard time staying awake in the dimly-lit, hot courtroom; even Knox seemed to nod-off a bit. As Dr. Stefanoni took the stand, Judge Claudio Pratillo Hellmann joked about it saying, “I’m glad to see you have no slides,” he said with a wry smile. Still, Dr. Stefanoni did, however, use more slides. Under questioning by prosecutor Manuela Comodi, Dr. Stefanoni defended the methods and equipment used in the investigation.


Dr. Stefanoni told the court that the machine used for the DNA examination was clean, and she rejected suggestions that the clasp had been contaminated. Dr. Stefanoni said the knife was tested in a lab six days after investigators had analyzed a trace of Kercher’s DNA, and she insisted that contamination did not occur.

Dr. Stefanoni also insisted that during period of 46 days after the killing that it took to collect the bra clasp, “nothing from outside the victim’s room was brought inside.” She insisted that out of 133 specimens analyzed in the house of the murder—including 89 in Kercher’s room—Sollecito’s genetic profile was only found in a cigarette butt in an ashtray, mixed with Knox’s. “If Sollecito’s DNA had somehow traveled from the butt to the clasp, then there would be Knox’s DNA as well on the clasp,” she said. This is something that I have posited and discussed long ago (SEE HERE for further explanation).

Also called to the stand by the prosecution was Giuseppe Novelli, an expert on human genetics at Rome’s Tor Vergata University. Novelli said he reviewed the prosecution’s procedures and he “absolutely excludes” contamination on the knife and bra clasp. Then he made a very valid point of common sense. “If the origin and vehicle of contamination is not proved, this is just a hypothetical theory,” Novelli said, adding that experts did not state precisely how the two items may have been contaminated with DNA.

The prosecution also called Francesca Torricelli, the director of a Genetical Diagnostic Center at the University of Florence. She argued that the DNA evidence was credible, and she had looked at the data and came to the same conclusions as Dr. Stefanoni. Professor Torricelli assured the court that Meredith’s DNA was on the blade of the double DNA knife.


Vecchiotti (above w/ Conti) testified in an earlier hearing that the knife tested negative for blood and the amount of DNA said to be Kercher’s was so low that it could not be examined again with any conclusions. But Torricelli refuted this claim, saying that she had witnessed the work of Vecchiotti and Conti, and that the machinery they used during their investigation could check extremely low quantities of DNA. Meanwhile, Novelli told the court that for him, and others, it was not a question of “quantity of DNA, but rather quality” to carry out a successful examination.

Outside the courtroom, prosecutor Comodi said she considered that Stefanoni and Novelli had clearly proven the good work they had done.

Facts About the Double-DNA-Knife & Bra Clasp

Let’s take a closer look at the alleged murder weapon that will be examined and reported on in the months to come. All DNA evidence was overseen by Dr. Patrizia Stefanoni, forensic biologist and Chief of the Italian Scientific Police Unit in Rome. Dr. Stefanoni is respected around the globe and she had no vested interest in a particular outcome—she had no dogs in this race, per say. The Marietti knife, which was found in the cutlery drawer in Sollecito’s kitchen and marked “Exhibit 36,” has a 6 ½ inch stainless steel blade. Dr. Stefanoni testified that the knife possessed Knox’s DNA in a groove on the black handle of the knife and Kercher’s DNA on the tip; hence the title "the double DNA knife."


When confronted by police about the knife early-on in the investigation, Sollecito coolly explained that Meredith’s DNA should be on the blade of the knife because he accidentally pricked her with it while he was cooking a fish diner at his place. “The fact that Meredith’s DNA is on my kitchen knife is because once, when we were all cooking together, I accidentally pricked her hand,’’ he said. It was later proven that Meredith had never even been to Sollecito’s place. In fact, she had only seen him once or twice very briefly: remember Knox and Sollecito had only met a week before the murder. Furthermore, the girls who lived in the flat testified that they had never seen the knife at the cottage at Via Della Pergola 7 (site of the murder). Sollecito has not spoken about that statement since and has yet to retract it; he did exercise his right to silence during the original trial.


Several doctors testified that the knife matched the most significant wound on Kercher’s neck—the deepest and fatal wound. During an independent review of the forensic evidence in 2008, Dr. Renato Biondo, the head of the DNA unit of the scientific police, reviewed Dr. Stefanoni’s investigation and the forensic findings. During his testimony he confirmed that all the forensic findings were accurate and reliable. Dr. Biondo and Dr. Stefanoni (Shown in pic above) are among the top forensic experts in all of Italy. The Kercher family hired their own DNA expert, Professor Francesca Torricelli (Director of a genetic facility at Careggi University Hospital). She also agreed with Dr. Stefanoni that Meredith’s DNA was on the blade of the double DNA knife. Moreover, by the admission of Sollecito himself; Meredith’s DNA was on the blade, as he recalled pricking her with it while preparing a meal at his apartment—not only was he not surprised, he confirmed it to be true.

And, as for the bra clasp: there is absolutely no question whether Sollecito’s DNA was or was not on it—it was! There is less than one chance in a trillion that this was not Sollecito’s DNA. This is a mathematical fact, as plenty of his cells were present to provide a reliable test (1.4 nanogram or 1400 picograms—which contains approximately 160 cells). The only thing that can be contested was contamination from the machine, which is virtually impossible to prove—and would almost have to be performed by monkeys to occur, because of the large amount of cells present. Or, due to some type of physical transfer, prior to removal or testing, that would involve an incalculable improbability, considering that Sollecito’s DNA was not found in the cottage anywhere else (other than a cigarette but).

Although the knife & clasp are two pieces of evidence being re-examined, there were a total of 23 separate pieces of forensic evidence in the case.