Wednesday, April 22, 2009

Understanding Why The DNA Is On The Knife

Posted by Peter Quennell

[click for larger image]

Our DNA poster Nicki has been 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.

However, as the knife appeared to have been thoroughly cleaned with bleach, some remain intrigued that any DNA at all was found.

Here is a short piece explaining why. This article by Juliet Lapidos was posted on the Slate site in November 2007. But we haven’t seen better, and it is still often referred to.

Slate 20 Nov 2007
How To Clean a Bloody Knife: Does DNA come off with soap and water?
By Juliet Lapidos NYTimes Staff Writer

Investigators in Perugia, Italy, have found new evidence linking a 20-year-old American exchange student, Amanda Knox, to the brutal stabbing death of her roommate, British student Meredith Kercher. According to the latest reports, Knox and her Italian boyfriend, Raphael Sollecito, cleaned the alleged murder weapon””an 8-inch black-handled kitchen knife””with bleach. Nevertheless, police discovered Kercher’s DNA on the tip and Knox’s DNA by the handle. Is it possible to clean DNA off a knife?

Yes, if you know what you’re doing. Knox and Sollecito were on the right track: Bleach contains sodium hypochlorite, an extremely corrosive chemical that can break the hydrogen bonds between DNA base pairs and thus degrade or “denature” a DNA sample. In fact, bleach is so effective that crime labs use a 10 percent solution (one part commercial bleach to nine parts water) to clean workspaces (PDF) so that old samples don’t contaminate fresh evidence. Likewise, when examining ancient skeletal remains (PDF), researchers first douse the remains in diluted bleach to eliminate modern DNA from the surface of bones or teeth.

So, why did Knox and Sollecito’s bleaching gambit fail? It’s difficult to swab a knife thoroughly. Dried blood can stick to the nooks and crannies in a wood handle, to the serrated edge of a blade, or become lodged in the slit between the blade and the hilt. With help from a Q-tip, it’s possible to eliminate most stains, but what’s not visible to the naked eye might still be visible to a microscope, and sophisticated crime labs need only about 10 cells to build a DNA profile.

Bleach is perhaps the most effective DNA-remover (though evidently no methodology is failsafe), but it’s not the only option. Deoxyribonuclease enzymes, available at biological supply houses, and certain harsh chemicals, like hydrochloric acid, also degrade DNA strands. It’s even possible to wipe a knife clean of DNA-laden hair follicles, saliva, and white blood cells with generic soap and warm water. The drawback to this last method is that the tell-tale cells don’t just disappear once off the knife. They linger on sponges, in drains, and even in sink traps, where wily investigators search for trace evidence.

There appears to be a great deal more DNA evidence than merely what is on the knife, of course, and early in the trial the known luminol-evidence universe also expanded.

The court was told that AK-sized and RS-sized footprints appeared under luminol on the floor of Filomena’s room.

Nicki’s two Powerpoints on the DNA can be seen here and here and Kermit’s Powerpoint (pre the new evidence) on the luminol can be seen here.


Patrizia Stefanoni is quite unequivocal about the double DNA knife. She states it is Meredith’s DNA on the blade. Dr. Renato Biondo, the head of the DNA Unit of the scientific police in Rome, has provided independent confirmation that this forensic finding is accurate and reliable.

It should be noted that the double DNA knife had been cleaned with bleach and DNA was still extracted from a microscopic groove near the tip of the blade, which means the knife must have been saturated with Meredith’s DNA.

The other forensic evidence is just as damning:

There are at least three instances of Amanda Knox’s blood mixed with Meredith’s blood in the bathroom at the cottage. This will be very difficult for the defence lawyers to explain away. Perhaps, Knox had a bloody earring and maybe a drop landed on a drop of Meredith’s blood, but in three different places?

An abundant amount of Raffaele Sollecito’s DNA was found on Meredith’s bra clasp. Patrizia Stefanoni and Dr. Renato Biondo have categorically excluded the possibility of contamination. This key piece of forensic evidence won’t be considered in a vacuum, but will be placed into context. Meredith’s bra was removed quite some time after she had been killed.

It makes no sense for Rudy Guede to have gone go back to the cottage to alter the crime scene in order to mislead investigators. Judge Paolo Micheli rightly concluded that the only person who had an interest in tampering with the crime scene, including staging the break in, was Amanda Knox.

Incidentally, Raffaele Sollecito’s forensic expert, Professor Francesco Vinci, claimed that he had found Knox’s DNA on Meredith’s bra.

The bloody footprints at the crime scene also implicate Amanda Knox and Raffaele Sollecito. Knox’s footprint was set in Meredith’s blood in the hallway outside Meredith’s room. Another bloody footprint in the hallway and the one on the blue bathmat in the bathroom have been attributed to Sollecito. It’s blatantly obvious that the two bloody footprints, which match Sollecito’s foot size, are not Rudy Guede’s.

Posted by The Machine on 04/22/09 at 10:29 PM | #

It will be very interesting to see the defence try to counter all the points of DNA evidence that you mention here Machine. It does no harm to reiterate these facts for new readers. They get me every time. What the HELL is AK’s blood doing mixed with Meredith’s? This is not disputed or minute DNA evidence. We have no sensible suggestion from the ever vague Ms Knox on how this happened. Knife or no knife, for me the mixed blood is about as damning as evidence can be. Just tell us the truth Amanda.

Posted by TT on 04/23/09 at 11:48 AM | #

I think we should remember that the defense will have a harder time convincing the jurors of contamination than, for example, in the OJ Simpson trial.

In the OJ trial, DNA evidence was a fairly new field, and a weak judge allowed the defense expert witnesses drone on for weeks about points which neither the judge nor lawyers fully understood, still less the jurors. I don’t think that will be allowed to happen here.

The International Standards which have been mentioned, if they were adhered to, also help the prosecution.

Also, here we seem to have much more ‘expert’ jurors. I believe that a couple are lawyers themselves.

A defense strategy based solely on ‘blinding the jurors with science’ seems rather risky.

This begs the question of what strategy can the defense adopt. In all the newspaper reports and postings on blogs we don’t seem to have had much, if any, discussion of this.

I would like to hear whether anyone has any idea.

The only strategy I have read of is to ‘admit to everything, except the murder’. This was used in the ‘Green Bicycle Murder trial’ in the early 20th century, and got an acquittal despite overwhelming evidence, covering up evidence, changing story, etc… sounds familiar?

Presumably, there are other ‘classic defense strategies’ that can be employed, as opposed to simply disputing every piece of evidence presented by the prosecution.

Posted by Kevin on 04/23/09 at 02:57 PM | #

The OJ Simpson case was the first and just about only other one I’ve looked at close-up.

A week after the murders I was in LA en route to Asia and I cruised by OJ’s and Nicole’s houses. (Nicole’s was in a noticeably more downscale area.)

The defense did take forever on the DNA; so of course did Marcia Clark, the prosecutor, and jurists later said they got bored out of their skulls.

In the Dateline documentary in December, the defense lawyer Theodore Simon warned that a whack-a-mole defense strategy could equally exasperate the jury.

He implied that the threat to the defendants is in the huge whole rather than the small parts, and simply whacking away at the small parts would not assure acquittal.

The defense supporters and blogs do seem to be mired in whack-a-mole, and seemingly increasingly losing traction as case-observers’ fact bases of the huge whole grow ever larger.

Might mitigating circumstances (drugs and psychology and family happenings) and a previous record of being nice be a strategy?

Problem with that route now is that vilifying Italy and the system and players seems to have hardened hearts rather than opened them… That might have to be reversed, for starters.

When Sollecito was being transported to Verona a few weeks ago and he emerged from the van at an autostrada rest-stop, he was yelled at angrily by the crowd there.

If Amanda’s PR has been a miserable flop in the one place that really matters, it sounds like Raffaele’s PR has fared no better.

Bottom line? “Gulp!!”

Posted by Peter Quennell on 04/23/09 at 03:40 PM | #

The big plus for the defense seems to me to be the defense lawyers, who are warm, likable, prominent, and respected locally.

The big negative for the defense seems to me to be, well, pretty well everyone still on the band-wagon.

Talk about a team shooting itself in all its own 50 feet… PR people in NYC rate this as a classic how-not-to.

Posted by Peter Quennell on 04/23/09 at 03:56 PM | #

A comment on DNA typing as ‘facts’:

Conventional legal scholarship has a deep-rooted commitment to the existence of objective facts, but offers relatively few resources for under-standing what makes/unmakes the credibility of scientific evidence in the courtroom. As a.o. PQ mentions the OJSimpson case was a central point of passage for highlighting the complexity of what is means to ‘understand’ the role of DNA as evidence in court procedures. The, since then, standardisation of DNA typing procedures can function as a mean to translate the world of professionals into lay commonsense understanding of science.

TJMK, thanks to the solid work of Nicky, Kevin, Peter, a.m.o., has done a absolutely terrific job to unfold the practice of forensic scientists, and hence to increase the commonsense understanding of when and how professionals produces – often – crucial points in a case. But standardisation of procedures itself does not produce meaning forlaypersons/juries. To convince juries - and make DNA (or other things) ‘evidence’ - the authority of science must be established contextual in every case.

The facts of science are transported into the minds of judges and juries through language codified into rules of admissibility, dramatically configured into opening and closing arguments, professionally packaged as expert testimony, and deconstructed through cross-examination. Yet the courtroom is basically also a theatre in which things are not only related but also shown in order to compel belief. And seeing – see ‘your own eyes’ - is an essential precondition for believing, but the right to see for your self is also in dispute when science comes under legal scrutiny in the courtroom.

In the OJSimpson case a video (TV), claiming to show the behaviour of the police and forensic personal at the crime scene, became an important tool for the defence to argue ‘contamination’ or malpractice. The video became a ‘virtual witnessing’ for the jury, repressing a more easy/recognisable way for commonsense to make sense of what has happened.

Also in the murder of MK, videos and statements regarding the behaviour of police/forensic personal on the crime scene, seems to have been set out to play a crucial role in the strategy of the defence. To establish a privileged point of view – to make DNA ‘facts’ in the eyes of lay persons - conflicts must be resolved, between direct and ‘virtual’ witnessing, and between lay and professional vision. How and who resolves such disputes and by what rules, emerge therefore substantial questions for the outcome of the process, and here the role of the judge, the legal system (including the frequency of meetings in the court!) and the (national) culture as whole is crucial (what is called the ‘economy of credibility’).

That’s why we se the defence of AK and RS are attaching everything that ‘moves’, no matter how small. In short: the strategy of the defence is – supposedly - to undermine the credibility of the system as a whole.

Best, Fiori (Firenze)

Posted by Fiori on 04/24/09 at 02:05 AM | #

“There are at least three instances of Amanda Knox’s blood mixed with Meredith’s blood in the bathroom at the cottage.”

Maybe I missed something…  what is the basis for this?  Where were the samples taken?

Thanks for all the thoughtful work/comments.

Posted by Sierra1049 on 04/24/09 at 03:23 AM | #

After seeing the photos of the crime seen and all the blood in the bathroom, I know I would never have taken a shower as Amanda stated she had early in the investigation.  Is she still sticking to that story?

What about the clothes dryer that was running when the police arrived?  I read somewhere that Meredith’s clothes were in it.  Does anyone have information on that? 

Were the police able to examine the mop and bucket that AK and RS had outside the cottage when the police arrived?  I would imagine there would be plenty of DNA evidence on those items unless they managed to dispose of it before their arrests.

Just how stupid are those two?  Why didn’t they just throw away the knife?  Was it a favorite of RS and he couldn’t part with it?  I am glad they have it, but it makes me wonder.  They are so far removed from reality.

If the outcome looks like they will be found guilty. will their lawyers try to claim “Not guilty by reasons of Temporary Insanity?”

Posted by BARBM on 04/24/09 at 10:39 AM | #

I agree with BARBM. AK and RS increasingly reveal themselves as stupidly arrogant and disconnected from reality. I believe the knife was found tucked away in a shoe box.

Given descriptions of the shameless antics displayed in the courtroom yesterday, it appears as if AK thinks she’s on her way to an Academy Award-winning performance on the witness stand. I think she’s in for a whopping surprise. The witness stand will be more like a hot-seat or truth box than the pampering spotlight she enjoyed when she played a starring role as victim speaking Hamlet’s soliloquy in the film that was made.

Posted by wayra on 04/24/09 at 03:06 PM | #

Does anyone have any idea how long the prosecution will be presenting all their evidence?

Also, are there transcripts in English available?

AK and SC have stood up on a few occasions to counter what has been said, although when the shop owner testified that AK was at his store at 7:45am the morning after the murder, she did not stand up to refute that claim!  Again, not exactly brilliant to keep bleach receipts in RC’s apartment.

According to the reports today, AK and SC were grinning and whispering to each other before the video of Meredith was shown.  I am sorry, I just don’t understand what they must be thinking.  Wayra is correct in AK liking to be in the spotlight! 

I admit that I do feel sorry for her parents.  What she has done has ruined them! They seem like very nice, average people.  A school teacher and an accountant.  You can’t get more average than that.  It seems to me that they may be realizing that their daughter is not so innocent.  They show the concern, even when AK doesn’t.

Her mother is going to be called as a witness and thus cannot attend the trial.  Is she being called for the defense or the prosecution?  I know the police listened into all their conversations in jail, could they have heard something in those conversations? 

Just to make sure I don’t upset anyone with my comment about AK’s parents, I do feel the deepest sympathy and sadness for Meredith’s poor family.  Their loss is the worst imaginable for any parent or sibling to endure.  I hope some day they will find peace. 
In 1999, we had the Columbine High School masacre here by 2 students killing 12 students and 1 teacher and wounding 23 other students. One father lost his daughter.  She had written in a diary about tolerance.  He then started a program that has now traveled around to schools throughout the country called Rachel’s Challenge.  It is designed to help students learn racial tolerance and understanding of all types of people.

Can someone come up with a fitting tribute in Meredith’s memory that would make a positive impact in the world?

For those who knew Meredith, would she like something started in her name and memory?

What about a book dedicated to her about safety when traveling and studying abroad?

Posted by BARBM on 04/24/09 at 11:51 PM | #

Good comment BarbM. We began with the idea of a memorial fund for Meredith and we are as keen as ever to see something that memorializes her. It is still on our agenda.

We are presuming the prosecutors are about at their half-way point. The DNA and the luminol evidence will take some time to present.

As far as we are aware Edda Knox is only to be a character witness (with some or many others) for the defense. Peoples’ level of sorryness for her seems to go up and down, depending on what she has said lately. The family initiated the no-holds-barred PR campaign, and has never offered condolences to the Kerchers. They were present at Salty’s when one of the prosecutors was slimed, and presumably could have have reigned things in.

But yes they are paying a heavy price and if AK is found guilty it wont let up.

Posted by Peter Quennell on 04/25/09 at 12:49 AM | #

I compared the photographs of the accused from day after the crime to various photos of them along the way to appearing in court published in Sky News and elsewhere, and I wonder if anyone has noticed such a huge change in their appearances. I want to share my thoughts about what I see.

During the last 12 to 14 months, I’ve been remodeling the inside of my house and the theme is Italian, Tuscan, Umbrian style, and as I cut stone in places here and there using hints from, in fact from the photos of Perugia on this site, I’m often reminded of this case. So often I think about how Meredith would be spellbound in life to replicate similar things.  To build a house, plant a garden, have kids, enjoy a great Italian wine, and with a wonderful husband and so on, and reminisce about when she attended college in Italy. The path of life is a way we derive so much of where we go, what we take along with us, and what we leave behind when we reach the fulfillment of life.  This has been robbed from her.

Looking at the photos of the accused, they have lost tons of weight for then until now. Sure, prison and the situation bare down hard on one… one willing to allow it.

Initially, from the earliest media coverae photos, I first noticed that Amanda and Raffaele appeared to have had a shower. Their hair was sparkling clean in the photo in front of the house at Villa De Pergola. It was the first thing I noticed when I saw the photos because teens / kids don’t shower early in the day. It was noon, and they supposedly slept late but had time to shower, mop, and clean a house before noon. My kids have never cleaned anything especially with bleach at all and never cleaned anything before noon. They never clean period. Its not a probative notion, but give me a break.

Anyway, AK and RS are kids. Kids. From what we see, they apparently are murderers or complicit in murder as well. Most likely they didn’t mean to do what they did or leave behind the legacy of death at their front door, but they did.  They will be found guilty and sentenced to much longer time what was meted out for Rudy.  That will be the conclusion of man’s justice.

But true justice for Meredith is a combination of so many things.  First its the conviction of people responsible for her death, and at least second, its the direction of the tangible feeling we take with us when we hack on stone in a place of our lives when we think of what a wonderful gift Meredith gave so many people during such a short place in time here with her family and dear friends.

When we remodel our homes, we will feel a presence moving close to us and when we look around, no one will appear to be there. Sometimes when we feel like we’re falling, a hand will gently catch us. Your Meredith will be there with her loving outstretched arms saying thank you for caring for her in time.  I know this because I’ve been there and know it touches you too.

Posted by tony on 05/28/09 at 08:48 AM | #

Tony, I too was struck by the facial changes, most notably in Sollecitto. His flesh now clings to the cheekbones, producing an almost plastic appearance. Gone is any “cuteness” that could have been attributed to him earlier, were he not indeed a murder suspect.
  While I can allow that the pair could not have thought their plans through very thoroughly ( unless they thought that threats of future violence or the mere intimidating presence of Raffaelle, the Son of the Prominent Urologist With Influence in High Places, would keep Meredith from running to the authorities, thus avoiding the need to silence her permanently) I completely believe there was malice aforethought. I can believe that Knox was high enough on her own newfound sense of power ( being able to control men, sexually) to not be thinking clearly about how Meredith might react to being robbed, confronted, raped, or, if killing had been on the original agenda, how messy a murder scene would be to cover up. I see Sollecitto as cocky enough ( note his comments about the stupid police, who do not find his flick knife in his pocket, and whose heads he could easily have run over in the road…) to believe he could pull off just about anything. Meredith was nobody to him; what did he care if she lived or died. Knox was the one with the personal vendetta. And Guede, I think, was affected deeply by what took place, but being of weak character, he chose to hide behind the distraction of his ipod and the chaos of the disco. I would not be surprised if Sollecitto had indeed threatened him with a knifing, should he breathe a word to anyone.
One thing I continue to wonder; without a shared first language, how concise a plan could two drug-addled people cococt? I see the argument overheard at the cottage as having taken place between Ak and RS,because things failed to go according to a misunderstood ‘plan’.

Posted by mimi on 05/29/09 at 07:24 PM | #

No doubt Guede has gotten the message from Bari loudly and clearly that it is easy to die in prison.
Perhaps the court and jurors will be getting the same message. PR firms tried and failed to silence Meredith’s distant voice. Wouldn’t it be ironic if threats of more violence silence her cries for justice.


Posted by jennifer on 05/29/09 at 11:59 PM | #
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