Tuesday, July 21, 2009

Case For The Prosecution: #1 The DNA Evidence

Posted by The Machine

[Above: Prosecutor Manuela Comodi, click for larger image]

1. Preamble

Nearly 200 hours over 23 days.

That is how long the prosecution took to present its voluminous case against Amanda Knox and Raffaele Sollecito, including time taken by the defense teams to conduct cross-examinations.

This series is a summary of the prosecution’s case in five parts, with a commentary on matters of key significance. The material has been reordered so that for example the DNA evidence presented at several points in the trial can all be described in one post here.

Sources used are the many published reports and some transcripts made of the testimony. All the main witnesses will be named in this series with a brief mention of who they are and their qualifications.

Two past posts that may aid in understanding the DNA testimony are Nicki’s post here and Fiori’s post here. All past DNA posts can be found in this area. 

2. The Large Double DNA Kitchen Knife

The double DNA knife is the knife that was sequestered from Sollecito’s apartment. Although there was an imprint of another knife at the scene, and one defense expert argued that there may have been yet another, it remains plausible that this is the weapon that was used to murder Meredith.

Dr. Patrizia Stefanoni was the leader of the forensic team from Rome that carried out all the forensic collections at Meredith’s house.  She testified unequivocally about the knife. A small sample of Meredith’s DNA was found to be in a groove on the blade, and Amanda Knox’s DNA was found to be on the handle.

Dr. Stefanoni noted that there were peculiar diagonal scrapes on the knife blade, which suggested that the knife had been vigorously cleaned.

Both Dr. Renato Biondo, the head of the DNA Unit of the scientific police, and the Kerchers’ own DNA expert, Professor Francesca Torricelli, provided independent confirmation that this forensic finding is accurate and reliable.

The defence teams’ forensic experts are not disputing that Meredith’s DNA was on the blade of the knife. Instead they are arguing that the knife was somehow contaminated for the DNA to actually be there.

Dr Stefanoni has firmly excluded this possibility of contamination in transit or in the laboratory. She testified that there hasn’t been a single instance of contamination in her laboratory for at least the last seven years, and every precaution was taken here to ensure that different traces were not mixed.

A police officer who led a search of Sollecito’s apartment added weight to the prosecution’s assertion that the double DNA knife had been cleaned with bleach. He testified that he had been struck by “the powerful smell of bleach”. 

When Raffaele Sollecito heard that the scientific police had found Meredith’s DNA on the double DNA knife in his apartment, he did not deny the possibility of the DNA being there.

Instead he made a claim about accidentally pricking Meredith’s hand whilst cooking at his apartment. “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.’‘

However Meredith had never been to Sollecito’s apartment and so it seems Sollecito could not have accidentally pricked her hand there whilst he was cooking. In attempting to explain the presence of Meredith’s DNA on the blade, he did so in a way easily disproved and seemed to further implicate Amanda Knox and himself.

3. Sollecito’s DNA On Meredith’s Bra Clasp

An abundant amount of Raffaele Sollecito’s DNA was found on Meredith’s bra clasp, and Dr. Stefanoni has excluded the possibility of any contamination.

This is the bra clasp that was collected some weeks after the first forensic collection and it was conceded that it should have been collected earlier. It was also argued that valid DNA evidence in other cases is often collected weeks or months or even years after the crime when a suspect object is unearthed.

Sollecito’s lawyer Ms Buongiorno is perhaps not surprisingly claiming that this bra clasp was also contaminated in the laboratory. The problem for them is to explain precisely where such an abundant amount of Sollecito’s DNA could have come from, and how it was so firmly imprinted.

The only other instance of Sollecito’s DNA at the cottage was found on a cigarette butt in the kitchen, seemingly an unlikely source at best.

It would seem unlikely that the judges and jury will conclude that the bra clasp was contaminated in a strictly controlled laboratory where Dr. Stefanoni follows rigorous laboratory procedures.  She is an internationally renowned and very experienced forensic expert and was part of a Disaster Investigations Team which identified disaster victims via their DNA.

Alberto Intini is the head of the Italian police forensic science unit. Andrea Vogt reported as follows in the Seattle Post-Intelligencer on Mr Intini’s testimony about the possibility or otherwise of contamination:

“Alberto Intini maintained that the crime scene had not been contaminated and pointed out that laboratory testing revealed none of the investigators’ prints or biological traces. Mr Intini said “In fact, it is the results that tell you if it was done correctly, and I can tell you that in this investigation there was not even one trace of any of our operators.”

He also pointed out that unless contamination has been proved, it does not exist. “It is possible in the abstract that there could have been contamination, but until this is proved, it does not exist.”

The prosecution demonstrated on the final full day of testimony that Meredith’s bra was actually removed with a knife some time after she had been killed.

Judge Paolo Micheli presided over the fast-track trial of Rudy Guede and committed Sollecito and Knox to trial. In looking at the identical evidence he asked “Who had a reason to come back, cut off Meredith’s bra, and move her body some time later?”

The present judges and jury might conclude differently, but Judge Micheli concluded that it would only have been done by someone who knew about Meredith’s death and had an interest in arranging the scene in Meredith’s room to point away from themselves. He discounted Rudy Guede, who apparently went home, cleaned himself up, and then was seen out on the town.

4. Knox Blood With Meredith’s

There were five instances of Amanda Knox’s blood or DNA mixed with Meredith’s blood in three different locations in the cottage in Via della Pergola: the bathroom, the hallway, and Filomena’s bedroom.

Amanda Knox’s blood was found mingled with Meredith’s blood in three places in the bathroom: on the ledge of the basin, on the bidet, and on a box of Q Tips cotton swabs.

Dr. Stefanoni testified that it would have been “strange” that three traces of blood with both Meredith’s and Amanda Knox’s DNA would have been left at different times.

Barbie Nadeau in Newsweek pointed out a reason why the blood stains must have been left on the night of the murder:

“Legal experts who follow this case have suggested that blood evidence cannot be dated and therefore could have been left weeks before the murder. But when Knox testified in her own defense in June, she conceded that there was no blood in the bathroom the day before the murder, effectively dating those blood stains to that night.”

Perhaps Knox had a bloody earring piercing, and maybe a drop landed on a drop of Meredith’s blood. But in three different places? Perhaps it is not surprising that the defence lawyers have not brought up the subject of the mixed DNA in the bathroom in their part of the trial.

Meredith’s blood was found on the top part of the light switch in the bathroom she shared with Amanda Knox. This suggests that it was deposited there when the light was switched on. Meredith’s blood was also found on the toilet lid. There were no DNA or other physical traces of Rudy Guede in that bathroom.

Knox’s DNA and Meredith’s DNA was also found mixed together in a bloody footprint in the hallway of the new wing of the house.

A mixture of Knox’s DNA and Meredith’s blood was also found in Filomena’s room. This seems to be compelling evidence because Knox had never claimed she entered Filomena’s room when she checked the cottage. This room was the scene of the alleged break-in, and there were glass fragments on the floor.

Meredith’s blood had been cleaned up in this room, but it was nevertheless revealed by luminol.

Barbie Nadeau concludes in a Daily Beast report that the mixture of Knox’s DNA and Meredith’s blood in Filomena’s room seems more incriminating than the double DNA knife:

“But perhaps more damning even than the knife was Stefanoni’s testimony that a mix of Knox’s DNA and Kercher’s blood was found on the floor in the bedroom of a third roommate, Filomena Romanelli.”


thanks Machine. i look forward to the next post. let’s hope closing arguments are this clear and concise!

Posted by mojo on 07/21/09 at 02:16 PM | #

Thanks, I was getting a bit confused with the Knox blood and DNA being mixed with Merediths- this has laid it out very clearly, your time, effort and passion is much appreciated.

Posted by Ginny on 07/21/09 at 06:59 PM | #

Thanks Machine for another one of your clear, illuminating and honest posts!

Posted by Nicki on 07/22/09 at 12:13 AM | #

Good Report!

I’m also making sure that is available to all viewers in Candace Dempsey’s blog.

I know that she deletes any posts presenting any “inconvenient truth” about the case.

But cutting and pasting is not that hard either. Eventually the truth will get to everybody.

Posted by Commissario Montalbano on 07/22/09 at 04:46 AM | #

This is an illuminating, clear and decisive report - excellent work! Many thanks.

Posted by Scooby on 07/22/09 at 03:08 PM | #

I have talked to Edda Mellas. She says that there is no proof of Amanda’s blood in Filomena’s room or in any of the footprints. What is being revealed by luminol is only footprints - which could have been caused by sth. else, she says.

Furthermore she says that there is no sign of a clean-up. Indeed, I had been wondering why the prosecution never officially brought up this otherwise extremely vital fact - can we prove there was a clean up?

I know of the bloody footprint in the bathroom - but how do we know that the rest of the foot was not by chance free of blood - instead of its trace having been erased later?

Posted by Malwida on 07/23/09 at 12:10 AM | #

Hi Malwida,

Edda Mellas is not an objective or reliable source of information.

She has made numerous false claims. For example, she has claimed Amanda Knox only lied once and that there was no interpreter present when she was questioned.

Dr. Patrizia Stefanoni testified that Amanda Knox’s DNA was mixed with Meredith’s blood in Filomena’s room. She is an objective forensic expert. Edda Mellas is neither objective nor a forensic expert. It’s worth bearing in mind.

Luminol reacts to a variety of substances, including blood.

Dr. Stefanoni pointed out at the trial that biologists who regularly work on crime scenes can distinguish between blood and other reactive substances such as bleach and fruit juice.

The Italian housemates testified that they didn’t use bleach to clean the cottage and it seems highly unlikely that the footprints were set in fruit juice.

Judge Paolo Micheli agreed with the prosecutors that the crime scene had been tampered with and partially cleaned up.

There was an absence of visible bloody footprint leading from outside Meredith’s room to Sollecito’s bloody footprint on the blue bathmat in the bathroom.

It is clear that somebody had cleaned up the trail of bloody footprints that must have been left in the hallway.

Somebody had also cleaned up Meredith’s blood from Filomena’s floor. It was only revealed by luminol.

Dr Stefanoni said some of the bloodstains found in the bathroom were “slightly pink as if the result of being washed” and Gioia Brocci testified that multiple drops of blood mixed with water were found on the sink and the bidet.

Posted by The Machine on 07/23/09 at 01:12 AM | #


Thanks so much for pulling all the pieces together. It is reassuring to see all the facts presented with such care and precision. I am very hopeful that this kind of conscientious attention to the evidence will result in a guilty verdict against AK and RS come November.

Posted by wayra on 07/23/09 at 04:53 AM | #

Hey guys-

I seem to remember reading somewhere that the DNA knife found at Sollecito’s was in a shoebox in his closet.

Does anyone know about this? Or have I just read way too much about the case (and the defense’s claims about ‘mishandling’) and confused myself?

If in fact it was found in a shoebox in his closet, isn’t that sort of strange???

PS Malwida-
Edda Mellas will say (and pay!) ANYTHING to keep her daughter out of jail.

Posted by Autumn Stinar on 07/25/09 at 01:05 AM | #

hi autumn,

i also remember reading that the knife at sollecito’s was found in a shoe box.

i later read that after it was found—i’m not sure where, but maybe even in the knife drawer—it was placed in a shoe box by police before being transferred to a lab for analysis.

the immediate distinguishing feature of the knife—or the area surrounding the knife—according to the police, was the overpowering smell of bleach.

Posted by wayra on 07/25/09 at 01:52 AM | #

I think the knife was found in a kitchen drawer and placed by the police in a shoebox when they removed it.

The distinguishing feature of the knife was diagonal scratch marks on it, as if someone had vigorously cleaned it.

The officer who first entered the flat described a strong smell of bleach, but I don’t believe it was specifically associated to the knife.

Posted by malcolm on 07/25/09 at 04:59 PM | #

thank you, malcolm, for your more complete and much clearer explanation!

Posted by wayra on 07/25/09 at 08:26 PM | #

First, let me note as an ExPat living in Italy, I was horrified at the terrible murder of Meredith Kershner. I do not have links to, or sympathies for any of the accused. As you read my analysis below, please don’t think that I am supporting or denying the guilt or innocence of any of the accused. What concerns me is the presentation of evidence. 

I have lived in Italy for the past two years, working with the best and the brightest molecular biologists and geneticists that Italy has to offer. I was assigned here to help raise the bar on the quality of science that Italy produces. I also have over 25 years experience in the field of DNA analysis and mutation. I have developed and run genetic fingerprinting and DNA analysis since before the advent of PCR, automated sequencing or modern genetic screening. I can safely say that I am an expert in the field.

DNA evidence requires very rigid standards of collection and an unbroken chain of possession. The OJ Simpson case in the US is a perfect example of the results of a failed chain of possession mixed with corrupt or bias individuals in the Police. Sadly, I see some strong similarities in this case. In general, I have observed that Italy has neither the training nor the infrastructure to adequately handle the evidence. They often don’t have a grasp of even the basic elements of the process. There are a few inconsistencies that I find especially disturbing and suggestive of manipulation.

1. The Knife with two sets of DNA. The officer who collected the knife reported a “powerful smell of bleach” on the knife. This suggests that someone recognized the bleach would degrade the DNA beyond recognition. Yet the police lab still recovered both sets of DNA.  Bleach evaporates fairly quickly if left out in the open. The residual smell should dissipate in several hours to a day. If the knife really had enough residual bleach to be detected how many days later?- then it should have been plenty strong enough to wipe out all long strands of DNA needed for successful DNA analysis. 

If, on the other hand, there was no bleach used, and this was a shared knife from the shared kitchen, then standard washing wouldn’t remove DNA effectively, and I would expect DNA from ALL of the housemates to be detected, especially on the handle. Yet only the DNA the supported the prosecution’s pre-existing theory was reported. Finally, despite Dr. Stefanoni’s assurance that no contamination have occurred in her lab in the last 7 years, we have seen similar claims by US forensics labs that were proven false.  By the way, someone remarked about the large size of the knife- it is a standard size kitchen chef’s knife, similar to what you can buy at the COOP, PAM, or Conads. I have three that size or larger in my kitchen.

2. Lack of DNA on the body. “If passive transfer of DNA is so easy to happen, and if Guede is the only one who physically attacked Meredith, how comes his DNA was found only in these three places on the victim’s body?”  I find this comment to be disturbing because it is so contradictory as to be disingenuous. The author of the comment correctly states that DNA samples can be recovered months or years after being shed (actually they can be recovered millions of years later.)  I find it highly disturbing and inconsistent that the forensics lab could recover and ID two sets DNA from a well bleached kitchen knife, yet not recover DNA from Mr. Guede (and not the other two suspects) from all over the victim’s body.

He did admit to having sex with her earlier in the day, correct? Was that sex so bad that she then scrubbed herself down with bleach to remove it? If not, then I would expect that there should have been at least as much of his DNA on a large portion of her body as there was on a bleached steel knife blade. Even if the DNA exchange occurred during the attack, it is unreasonable that his DNA was not found on other parts of her body if he participated as described. DNAses on the skin simply wouldn’t degrade it adequately. So the forensic lab can pull up DNA off of bleached steel but not off of porous skin or clothes. The two scenarios are pretty much mutually exclusive.

3. The Clasp. “DNA is NOT easy to transfer. Dr Stefanoni is absolutely correct when she says that “transfer of DNA must not be taken for granted nor it is easy to happen, and more likely to take place if the original trace is aqueous, not if it is dry”. Oh, if only it were so. Many years ago, my lab spent 6 months chasing down some erroneous gene mutations. It turns out that someone had been working on a plasmid carrying a similar gene two labs down, and it did indeed pick upon an air current and fly across to our bench. 

DNA is incredibly easy to transfer. How much of the dust in the air in your house is made up of shed skin cells? How many skin cells does it take to test positive for genetic fingerprinting? Using modern techniques, just a few. Investigators walking through the house over 47 days disturbed both the dust and bra clasp (found in a different place that where it was first cataloged.) A forensic lab shouldn’t even admit such a piece of evidence to their facility. It is already contaminated and the chain of custody broken after the original identification (and lack of gathering).

Summary- The DNA evidence presented strikes me as not just grossly misleading, but manipulated and contrived.  It should never have seen the light of day. If it was false, then it begs the question of what else has been contrived by the police or prosecution in their quest to convict the accused. Again, what I presented here is not to support or condemn the accused, but rather to wake up the many concerned friends and family that for there to be True Justice for Meredith, there must be truth in the justice. I can not find that in the evidence as I have seen it here. Sadly, this case smacks of the kind of manipulation that we see on both sides of the Atlantic in high profile cases when the Prosecution is looking for a glorious “Kill”, rather than truth or justice.

Posted by Siena123 on 12/09/09 at 05:47 PM | #


Thanks for the comments - though generally I find them highly speculative, and you do not demonstrate a convincing knowledge either of the case, or of its forensic evidence.

And for all our readers to know: NONE of the serious US-forensic scientists who have critically discussed the strength of the DNA evidence against Amanda and Raffaele has EVER suggested manipulation. That’s a very harsh insult, which is extremely rare among peers.

This lack of professional demeanor makes me very sceptical upon the validity of your claimed credentials. No guest among Italian molecular biologists will attack a colleague in this way - and with such vague arguments.

And it seems utterly unreliable that you have “observed that Italy has neither the training nor the infrastructure to adequately handle the evidence. They often don’t have a grasp of even the basic elements of the process.”

With certainty Italy has very good scientists within molecular biology and related fields. Likewise their forensic police are very well educated and have long practice in handling crime sites and evidence.

Italian researchers are internationally avant-garde within research of DNA profiling of relatives.

I want detailed examples of the cases/laboratories in which you have made the observations you claim, or I will conclude that you are not trustworthy, and that you are deceptive about your sympathies and credentials.

When you claim about DNA “actually they can be recovered millions of years later” you mix up things in a profoundly unprofessional manner. DNA from old bones are not ‘recovered’.

And we have here the possibility to perform DNA tests on the items, and sometimes it is possibly to perform genetic engineering and reproduce the material. But here it is not epithelia cells from touch by hand, which we – for absolutely obvious reasons – do not know if we can detect ‘million of years from now’.

Being a researcher myself - just another non-particular-noticeable common PhD among 1000 others, with 25 years of experience (not molecular biology at all) - I agree that a statement from one person (f.x. Patrizia Stefanoni) cannot be considered a proof.

But – as always in science – the authority of a statement is reflected in the scientist’s standing among peers, and Biondi and Stefanoni have excellent reputations among peers – in Italy as well as internationally.

This gives Stefanoni’s word weight, and science feeds itself from controversies among peers - how would we then ever get wiser?

Nicki in an earlier post here on TJMK has been very careful not to exaggerate the impact as evidence of the DNA on the knife found in Sollecito’s apartment.

She accepts that in the eyes of the court there could be question marks over the size of the sample and the fact that the tests could not be repeated.

My further comments and corrections:

- Rudy did not have sex with Meredith; he tried to rape her, but did not succeed. Guede’s DNA (from epithelial cells) was found inside Meredith, on the right side of Meredith’s bra, mixed with Meredith’s DNA on her purse zip, and on the left cuff of Meredith’s light blue sweater

- Collection of the knife: The officer reported a strong smell of bleach and this smell could easily have come from soft materials in the drawer, the handle of the knife, or drops hiding in the slit between handle and blade, or from other soft and receptive objects in the drawer. Identification of an item of interest for an investigation is – as always – at random; the police collect different items which for one reason or another have captured their interest. Intuition is de facto a strong competence in police work.

- When you claim that cleaning with strong bleach would have wiped out all DNA, and cleaning with thin solution of bleach would have left DNA of all the household, you imply manipulation, and suggestion that many people were in practice of using the knife. Probably not, as the knife was found in Raffaele’s kitchen drawer, and Raffaele was, as we know, not a very outgoing type. It seems likely that only Raffaele’s or Amanda’s DNA could be found on the knife. Amanda’s was found - not so interesting in itself - but devastating when Meredith’s DNA was found at the blade of the knife.

- You suggestion that DNA is incredible easy to transfer by air is LOGICALLY RIDICULOUS. If shed skin cells in the air produce strong genetic fingerprints, then DNA tests would be completely useless as evidence in court. Then DNA could not be taken as proof that a suspect really touched the knife or the gun under investigation, or if he was just passing by while scratching his nose.

- DNA evidence CAN be erogenous, we know that from a.o. the Innocence Project in the US. And DNA samples CAN be contaminated, BUT your speculations are far from what are – within the professional communities of forensic scientists – the accepted problems of DNA testing.

- Most erogenous matches seem to be due to degenerated DNA profiles, or wrong matches from cold hits (result from searches in a data base with DNA profiles)

- contamination is VERY RARE, but IF it occurs (known cases), it occurs mainly in the laboratory, as cross-contamination of samples, but EXACTLY because the bra-clasp was left on the floor, and tested 46 days AFTER all other items collected, it is highly unlikely that it is contaminated.

Posted by Fiori on 12/09/09 at 11:57 PM | #

Apparently a few American scientists did a review of the victim’s DNA found on the tip of the knife entered into evidence; written up in this article:


This letter was previously on scribd, but has been removed. The article quotes the letter as stating:

“To minimise the risk that some peaks arise from contamination, most US labs only count peaks above a height threshold of 150 relative fluorescence units (RFUs) and all dismiss those below 50. The trouble with the DNA found on the knife is that “most of the peaks are below 50”, says Greg Hampikian of Boise State University in Idaho, who signed the letter and reviewed the DNA evidence”

“When this happens, samples can be rerun, but this doesn’t appear to have been done in the Knox and Sollecito case. This means contamination cannot be ruled out, the open letter claims. The same lab may also have been running DNA profiles from other evidence in the case at the same time, it says, and tiny amounts of this could have contaminated the knife samples.”

However, I ran across this statement from a case in 2006 in Denver, CO (USA)


“Lisa Calandro was the DNA laboratory supervisor in the Forensic Science Division at Forensic Analytical, a private forensic and environmental testing and consulting firm in Hayward. She testified as an expert for the prosecution in forensic DNA analysis.”

“Calandro’s laboratory uses 100 RFU as a “normal detection limit,” although analysts will go as low as 50 RFU if it is fairly certain there is a peak. It would be necessary to be somewhat cautious about any interpretations below 100 RFU since the lower the RFU, the greater the possibility of detecting electronic “noise,” rather than a true peak. The lower the RFU number, the higher the amount of data that can be interpreted. But there is also an increased probability of detecting “artifacts,” i.e., not real DNA.”

Posted by pat az on 12/10/09 at 02:36 AM | #

Ciao paz az,

Happy for your post, which confirms my critique of Siena123, and the fairness of the DNA-testing.

I’ve read these reports (and others), and as you also have read them you can confirm that these scientist argue within established scientific conventions and with professional conduct – au contraire to Siena123, which makes me doubt his credentials.

Your Denver reference reveals that also in US, forensic scientists go as low as 50 rfu, and still find it proper to use the DNA test as evidence in a trial.

Getting a match from low point rfu’s needs, as stated, the utmost caution, and the chance of getting a wrong match on a cold hit with a partial DNA profile is logically higher, than with full-profile match.

But the match in this case is not a cold hit. It is a comparison with a known DNA profile, Meredith’s, and as Meredith’s DNA profile is not ethnically ‘local’, the chance of getting a random match (that the obtained profile matches the profile of somebody else being at the same place the same time) is still incrementally small. (Se a.o. the Thompson report: “The potential for Errors in Forensic DNA testing”).

The ‘low peak’ DNA test is the test on the blade of the knife. Not the test on Meredith’s bra, which had high peaks.

As stated by Nicky earlier, it is fair for the defence to investigate the process of how the DNA profile on the knife blade is obtained, especially in the light of the lack of possibility to re-run the test.

Stefanoni has explained that the profile was obtained by extending the usual procedures but NOT violating scientific conventions or technological performance. Which your Denver report confirms. To accuse Stefanoni of manipulation is utterly offensive; though to ask her to reveal the scientific and technological background of the findings are usual.

We should be tremendously sceptical about the possibility of contamination of the DNA samples, as contamination is extremely rare, and it seem ridiculously out of (statistical) proportion if there should be two (INDEPENDENT) incidents of contamination in the same trial (and only for Amanda and Raffaele, and not Rudy).

Posted by Fiori on 12/10/09 at 03:36 PM | #

In my review, I neglected to point out that I was reviewing the evidence, as presented on this website, which I take to be a frank summary of the case. I will freely admit that I have not obsessively watched the case, but was only responding to what I have read here. obviously I would be better informed if I delved more deeply into the court records. Still, I think that many of my points were valid. Also, it seems silly to assault my credibility and motivation. I have read details that I found suspicious and have questioned them. That is just basic science. Also,I won’t go into my specific credentials for a couple of reasons - I am not allowed to in my current position, and I wouldn’t actually trust the local Polizia even if I could.

Now, rebuttals of rebuttals-

1. The Knife- have you ever performed surgury or cut up medium to large animals? After the first minute or two, your blade and handle will be saturated with the animal’s blood. If finding the victim’s DNA on the blade is understandable, but how could it not be found on the handle after, what, 47 cuts? THAT is not in the realm of credible. There should have been overwhelmingly more of the victim’s DNA on the handle than of Knox’s. Also, where did the Knox DNA come from here and in other parts of the house? I understood that there were indications of Knox’s blood. Did she show any fresh wounds when arrested that would explain this?

2. The Bleach- I am still seeing a descrepancy here- was the bleach smell from the knife, or from the kitchen. If you have worked in lab with bleach, then you know that the smell usually dispates within an hour or less after cleaning a surface. On very porous materials like cloth, it can last consideribly longer, especially if used at bottled strength. But if it was on the blade, it really should have cut up the DNA into fragments that were non-recoverable. I find the policeman’s comment taken for the court record suspiciously convenient. Again,it is just too similar to the behaviour of Mark Furman (sp?), the policeman in the OJ Simpson case.

3. The Bra clasp- here is another example of what any court should be wary of- a piece of evidence that shows obvious displacement and tardy collection. Let’s skip intentional contamination. How did the bra clasp move to a new location. Did someone step on it and it stuck to their shoe? If so, then whatever else they ground into while walking across the floor would then grind into the clasp. This is how DNA(in the form of shed cells, etc) move easily across rooms. Again, since I didn’t see it discussed here, was the victim’s DNA also found on the clasp? I presume that it was, if it is supposed that she was wearing the bra at the time of the attack.

4. Critisism of Italian Science Culture- Sorry, but it is well deserved. The newly revived PhD program here is a welcome attempt to revitalize the system, but across hospital labs, academic labs and industrial sites, I have seen poorer standards than when I inspected facilities in South America and SouthEast Asia. That may be a bitter pill for you to swallow, but it doesn’t make it any less true.

5. Final Point of Order- Italian Prejudice against outsiders is a real phenomena. My wife and I have experienced it for two years. It just makes Italy like any other place on Earth. Everybody likes to think their culture has risen above it, but all of our cultures are guilty of it. Think about it the next time you see one of those little Black Sambo dolls that seem to be sold in many stores in Italy. It is not just the Nord Party that is guilty of racism….

Posted by Siena123 on 12/10/09 at 06:28 PM | #


It’s not Meredith Kershner, it’s Meredith Kercher.

Posted by vanja on 12/11/09 at 01:56 AM | #

Siena 123:

Responses on where I’m currently standing on these issues:

1- scarcity of DNA on the knife- if the knife was cleaned with bleach, then you would expect that a lot of the DNA evidence would be cleaned, and what would remain would be in hard to reach crevices. A recent Slate.com article asks “is it possible to clean dna off a knife” found at the link below. While it states ‘swab’, and leaves open the question of, say, a thorough dunking, it does say it can be difficult to remove all things that a microscope might reveal.  http://www.slate.com/id/2178383/

2- the ‘smell’ of bleach- i agree that its ambiguous as to whether the smell was related to the knife, the kitchen, or the apartment. It was noted during the collection of the evidence.

3- bra clasp; apparently they only noticed it missing from the bra ‘after sifting through’ the accumulated evidence, and went back to locate it. Its likely that nobody understood the importance of it on the first collection.  Arguments are put forth that dna tests are often performed on evidence collected from a scene significantly after the initial scene collection; i cannot attest to the truthfullness of that. However, the amount of DNA on the clasp is said to be ‘abundant’. There was no other DNA collected in the bedroom pointing to Sollecito. I don’t know if they did any DNA tests on the floor in that room to see if it could have been picked up from the floor; or if DNA was found on the inside of the clasp that would suggest a casual transferrence from scraping the floor was not possible. The victim was wearing the bra at attack, but it was removed after death; it is pretty easy to come up with a scenario where moving the body after death and cutting the bra, the clasp would only collect DNA from the person removing the bra. (Bra clasps if you don’t know are usually protected from scraping the wearer’s skin by a flap of fabric, thankfully!)

Onto a previous point, I looked further at the issues of LCN testing of DNA, and what some of the blogs that are supportive of Knox’s innocence state, linked in the ‘trackbacks’ below. Without knowing the testimony on the stand or the procedure followed, there do seem to be some questions of procedure that I have not found a clear reference to an answer.

However, in doing so I concluded that the knife DNA may not have been as big a factor in the juror’s minds as the American media make it out to be - the victim’s DNA on the knife implicates Sollecito; the defense’s eventual argument that the victim’s DNA was -not- on the knife perjures Sollecito in the eyes of the jury. The defense can’t have it both ways, and it looks like they tried.

Posted by pat az on 12/11/09 at 02:44 AM | #

This is not a criticism of anybody, and I support the guilty verdict, but I’d just like some clarification.

It was my understanding that the policeman who found the knife said that the room the knife was found in smelt of bleach, not the knife itself.

I also think it is of far greater significance that Sollecito didn’t deny it at all but admitted the DNA on the knife was Meredith’s, and provided an excuse for its being there.  I think the fact he did that is of far greater value than the argument as to whether the sample is a reliable enough match or not.

With regards the DNA in Meredith’s room, I too was taught at University that human DNA was very easy to contaminate, which is why very rigorous procedures were always put in place for examining it.  (However I was also taught that DNA had a very definite shelf-life which is why Neanderthal DNA was so difficult to amplify using PCR.) 

But if older material from archived cases is still perfectly viable (and think how many people must have come in contact with it), then what is the problem with Sollecito’s DNA being found on the clasp?  Sollecito had very rarely been to Meredith’s house then I wouldn’t have thought it would have been that easy for such a strong sample of his DNA to contaminate anything (although stranger things have happened).

Also, if Meredith’s room was that easy to contaminate then how come her room wasn’t filled with the DNA of her housemates that actually lived there?

I also understand that Amanda’s DNA was found on the bra strap, according to both Guede’s and Sollecito’s teams, but denied by Knox’s team. 

Like Pat Az, I feel it does seem a case of the defence teams trying to have their cake and eat it.  That is, where some DNA might support the defence, it’s reliable.  Where is supports the prosecution, suddenly it’s contaminated, it’s not reliable.  But that is the job of the defence I suppose, to continually raise doubts about the prosecution’s evidence.

I also do not think that the case rests on the knife and the DNA, and people are putting far too much significance on it.

We have no idea just how much was accomplished by the guilty parties before the police turned up.  But a great deal more information from all sources all taken together, gives us this better picture as to guilt.

Posted by Tim on 12/11/09 at 11:40 AM | #

Backracking to the talk between Sienna 123 and Fiori regarding “The DNA Evidence”.

I am not a scientist and I leave them to discuss the scientific evidence. Anyone is, I assume, entitled to comment on this site, even if to throw doubt on the evidence.

Sienna 123 did this (over a year ago) and made some interesting comments about the DNA evidence, which I thought were effectively dealt with by subsequent comments. And, of course this has all been much discussed. I certainly do not want to dredge all that up again.

For anyone coming to this chat again, I simply want to make the following comments in support of Fiori’s doubts about the credentials of Sienna 123.

Just read the second and third paragraphs of Sienna’s comment of 12/09/09. Then read the first paragraph of his comment of 12/10/09. He says he can safely tell us that he is an expert in the field. After all he:

1. Has worked with the best and the brightest molecular biologists and geneticists that Italy has to offer.

2. Was “assigned” to Italy to “help raise the bar on the quality of science that Italy produces”.

3 Has 25 years experience and has helped develop and run genetic fingerprinting and DNA analysis since before the advent of PCR, automated sequencing and modern genetic screening.

Quite a claim.

Fiori rightly challenged him to produce his credentials, which he declined to do, stating that “I am not allowed to in my current position”.

I am sure my comments also occurred to other readers at the time; but they are worth re-stating for the sake of completeness.

1. Anyone can anonymously assert they are an expert. Since this is obvious the only point of making such a claim is to establish credibility; in this case for his comments on DNA that followed.

2. No self-respecting scientific expert would ever lay claim to expertise without identifying himself and his qualifications. This is just not done in the scientific community. It is also highly unlikely that such a high caliber expert would actually blog.

3. His claim that he needs the cloak of anonymity to partake in the chat is feeble. He says that he has been working for 2 years in Italy with the brightest and best etc. Given his CV, a pioneer in the field and his special assignment, surely his employers, the brightest and best etc, would twig - assuming, that is, that they are following the blog? So much for the need for anonymity.

4. As Fiori points out, his other comments about the Italians are gratuitously offensive and just plain wrong.

5. His language is unscientific. No scientist would say ” ..it should have been plenty strong enough to…”

Come on Sienna, if you read this, own up. Even though your game is long blown.

The point of all this is that Sienna is surely just another pro Amanda campaigner and his doubts about the DNA were merely a more sophisticated attack than might have been expected from that camp.

Posted by James Raper on 12/07/10 at 05:07 PM | #

Hello James. I agree with the points you make. 

I remember when I read Siena’s post my suspicions being raised about the credibility of the poster as a ‘scientific authority’.  I felt it suspect that he/she didn’t establish their credentials as is normally the case in scientific discourse.

Some of the things stated just didn’t ring true and as you say, anonymity would have been compromised had he really been on such a specialised scientific assignment: ‘Was assigned to Italy to help raise the bar on the quality of science that Italy produces’.

I suspected that the person behind this may have been from the pro Knox camp, trying a different, more sophisticated, tactic.

Posted by Lola on 12/07/10 at 05:36 PM | #

Hi James and Lola. Great points. Yes Fiori really knows her stuff. And the Italian labs work closely with the FBI labs. There is cross-training.

At a guess, Siena123 (who is still registered here but perhaps wisely decided to call it quits) was Chris Halkides, or Ron Hendry, both notorious for pomposity.

You can google how these two spurious experts each claim to have “solved the case”. Not respected or for that matter even known about in Italy. None of them have been used by the defenses, or put on the stand to testify and be cross-examined.

Posted by Peter Quennell on 12/07/10 at 07:00 PM | #

Hi Peter, the Knox supporters are certainly getting desperate.  I am glad you have uncovered them!

Posted by MHILL4 on 04/19/14 at 06:49 PM | #
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