Sunday, January 24, 2010

Forensic DNA contamination

Part IV in a series on the Knox/Sollecito case

Before we examine the bra clasp in the murder of Meredith Kercher, we need to explore the problems of forensic DNA contamination. This background may also help to explain the problems relating to the DNA sample culled from a kitchen knife discussed in part I of this series.


In An Introduction to Forensic DNA Analysis, p. 14, Norah Rudin and Keith Inman “define contamination as the inadvertent addition of an individual’s physiological material or DNA during or after collection of the sample as evidence…A contaminated sample is one in which the material was deposited during collection, preservation, handling, or analysis.” When this is done deliberately, this constitutes evidence-tampering, although there is no bright line between tampering and contamination.

Proper collection of evidence

Dick Warrington has written two useful articles on contamination for Forensics magazine. He stresses the importance of changing gloves frequently and using disposable tools. If disposable tools are not available, one must clean them between handling different pieces of evidence. In the 2009 article he cautions, “If you pick up one piece of evidence and then pick up another piece of evidence you can transfer evidence from the first item to the second item. You can avoid this kind of cross-contamination if you remember to change your gloves before handling each piece of evidence.”

Sources of contamination

The polymerase chain reaction (PCR) technique is used to increase the amount of (amplify) DNA by a maximum of 2n times, where n is the number of cycles of PCR. Because n is typically greater than twenty, this process amplifies the amount of DNA in every sample by over one-millionfold.

In Forensic DNA Typing, p. 152, John M. Butler notes “Contamination implies the accidental transfer of DNA. There are three potential sources of contamination when performing PCR: sample contamination with genomic DNA from the environment, contamination from samples during preparation, and contamination of a sample with amplified DNA from a previous PCR reaction (Lygo et al. 1994). The first source of contamination is largely dependent on sample collection at the crime scene and the care taken there by the evidence collection team (see Chapter 3). Environment contamination can be monitored only in a limited sense by ‘substrate controls’ (Gill 1997). The latter two sources of contamination can be controlled and even eliminated by using appropriate laboratory procedures and designated work areas (see Chapter 4).”

Footnotes for Butler

Gill, P. (1997) Forensic Science International, 85, 105-111.

Gill, P. and Kirkham, A. (2004) Journal of Forensic Sciences, 49(3), 485-491.

Lygo, J.E. et al., (1994) International Journal of Legal Medicine, 107, 77-89.

Dr. Donald Riley writes, “It is often said that the most critical source of PCR contamination is DNA from previous PCRs. Again, a PCR produces many DNA copies of the target DNA sequences. Due to shear number, these copies (called amplicons) are a hazard for future PCRs… However, a more dangerous source of contamination is what is called genomic DNA. This is DNA that hasn't yet been amplified. Genomic DNA doesn't have the high concentration of the target DNA copies but is a hazard because genomic DNA could produce an entirely false DNA profile. Full profile contaminants have been documented on multiple occasions and in multiple laboratories. Partial profile contaminants are more common and sometimes constitute a poorly recognized risk in using partial profiles in evidentiary samples as evidence. When contamination occurs there is rarely any way to confirm how it happened.” (emphasis added) The wonder of the PCR technique, its ability to make almost unlimited quantities of DNA, is also its danger.

Preventing and detecting contamination in the lab: the limits of negative controls

Donald Riley delineates some parallels between sterile technique and the techniques used in DNA forensics lab to minimize contamination. However, he also notes that clinically sterile equipment or reagents might still harbor DNA and that DNA samples lack an immune system to ward off contaminants. Moreover, good technique does not ensure a zero probability of contamination. Hence, there is a need for negative control experiments.

Terri Sundquist and Joseph Bessetti of Promega Corporation write:

A ‘reagent blank’ control consists of all reagents used during sample processing but contains no sample. This control is used to detect DNA contamination of the analytical reagents used to prepare the sample for analysis. In a separate negative control reaction, water is used instead of extracted sample or reagent blank. This negative control reaction is often referred to as the ‘no-template’ control and allows identification of contamination in the amplification reagents themselves.”

However, Donald Riley noted some deficiencies in negative controls, “Alternatively, the blank may show no profile, consistent with, but not proving that contamination didn't occur. Unfortunately, a few forensic DNA laboratories omit their controls…Good PCR technique is no guarantee that contamination didn't influence the results. Steps must be taken to try and detect contamination. Negative controls are blank PCRs that have all the components of the evidentiary PCRs but have no other DNA added intentionally. Fortunately, there are often two negative controls used, one when the DNA is extracted, and another when the PCR is set up. Any PCR signal in the negative control would warn that contamination has occurred. Unfortunately, the negative controls are virtually the only warning of PCR contamination. Negative controls may alert the analyst to general contamination occurring within the lab or the lab reagents. These controls don't offer protection against contamination occurring before the samples arrived at the PCR lab. Negative controls also can't rule out contamination of individual samples. The individual samples lack individual signs of contamination if it occurs. Unlike a human patient, a PCR is incapable of showing signs of infection (contamination) such as fever or undue pain. PCRs also have no immune system to ward off contaminants.”

Butler, pp. 152-154, implicitly recognizes the problems associated with the PCR amplification process:

“The possibility of laboratory contamination is assessed with ‘negative controls’ that test for contamination of PCR reagents and tubes. Basically, a negative control involves running a blank sample through the entire process in parallel with the forensic case evidence. The same volume of purified water as DNA template in the other samples is added to a negative control PCR reaction. If any detectable PCR products are observed in the negative control, then sources of contamination should be sought out and eliminated before proceeding further…To reduce contamination problems during the laboratory examination of DNA samples, all pre-PCR and post-PCR amplication reactions should be kept physically separate. Laboratory contamination is probably impossible to avoid completely, but can be proactively assessed with negative controls and staff elimination databases (Gill and Kirkham, 2004).”

Norah Rudin and Keith Inman (p. 15) state: “Once the sample is in the laboratory where it can be dried and chilled, the potential for contamination is mostly from other samples undergoing processing at the same time…Precautions include processing evidence and reference samples separately in space and time, restricting PCR product to an isolated room, and using controls to detect contamination in any batch of samples.” (emphasis added)

But William C. Thompson is clear about the limitations of negative controls,

“A false incrimination can also occur through cross-contamination among evidentiary samples. Even labs that are careful to test reference samples separately from evidentiary samples often process all of the evidentiary samples from a case together, creating the potential for false matches. I recently reviewed a case processed by the Los Angeles Police Department DNA laboratory in which samples from a bloody murder scene were being processed in the same batch as samples from items collected in a suspect’s house. Due to an analyst’s error in the case, DNA from the murder victim accidentally ended up in a control sample. This error was detected because the control sample was a “blank” which was supposed to contain no DNA. However, it was merely happenstance that the accidental transfer of DNA ended up in a blank control rather than another sample in the same batch. If the victim’s DNA had instead ended up in one of the samples from the suspect’s house, I believe that the error would not have been detected and would have led to a false laboratory report saying that the murder victim DNA had been found on an item collected in the suspect’s house. Defense lawyers need to think carefully about the potential for such errors because experience shows that they can and do occur.” (emphasis added)

Riley concurs, writing, “These controls don't offer protection against contamination occurring before the samples arrived at the PCR lab. Negative controls also can't rule out contamination of individual samples. The individual samples lack individual signs of contamination if it occurs.” The bottom line is that some instances of contamination probably go undetected.

Dishonesty involving controls

William C. Thompson delineates another problem:

“While most of the problems are due to inadvertent mistakes, a number of cases involving dishonesty have also come to light. DNA analysts have recently been fired for scientific misconduct, and specifically for falsification of test results, by a number of forensic laboratories, including labs operated by the FBI,14 Orchid-Cellmark (another large private DNA laboratory),15 the Office of the Chief Medical Examiner in New York City,16 and the United States Army.17 In all of these cases, the analysts were caught faking the results of control samples designed to detect instances in which cross-contamination of DNA samples has occurred.”

Footnotes for Thompson

14. See, U.S. Department of Justice, Office of the Inspector General, The FBI DNA Laboratory: A Review of Protocol and Practice Vulnerabilities, May 2004. Available online at:

15. Laura Cadiz, Md.-based DNA lab fires analyst over falsified tests, Baltimore Sun, Nov. 18, 2004.

16. Author’s interview with Robert Shaler, former Director of the OCME DNA Laboratory.

17. Associated Press, Worker in Army lab may have falsified DNA test result. Aug. 27, 2005; Memorandum For All Staff Judge Advocates Re: Brady Notice by Lisa Kreeger, Staff Attorney, Department of the Army, October 17, 2005 (on file with the author).

When the investigators and the DNA laboratory are in communication, the investigators sometimes make it clear that a certain result is desired. Thompson and colleagues (2003) write:

“Part of the problem is that forensic scientists refuse to take appropriate steps to ‘blind’ themselves to the government’s expected (or desired) outcome when interpreting test results. We often see indications, in the laboratory notes themselves, that the analysts are familiar with facts of their cases, including information that has nothing to do with genetic testing, and that they are acutely aware of which results will help or hurt the prosecution team. A DNA analyst in one case wrote:

‘Suspect-known crip gang member — keeps ‘skating’ on charges-never serves time. This robbery he gets hit in head with bar stool — left blood trail. [Detective] Miller wants to connect this guy to scene w/DNA …’

In another case, where the defense lawyer had suggested that another individual besides the defendant had been involved in the crime, and might have left DNA, the DNA laboratory notes include the notation: ‘Death penalty case. Need to eliminate [other individual] as a possible suspect.’”

The problem of having the laboratory be independent from the prosecution is a well-known one ( “The [National Research Council] recommends that forensic DNA analysis be conducted by an unbiased outside laboratory that maintains a high level of quality control and a low error rate.”

Case Studies of Contamination from Co-Processing of Samples

Thompson gives two examples of suspect identification on the basis of dubious cold hits:

“In one particularly interesting Australian case, DNA on the clothing of a murdered toddler named Jaidyn Leskie was linked, via a ‘cold hit,’ to a young ‘mentally challenged’ woman who lived hundreds of miles away and who, by all accounts, had never left her own village. Police could find no way to link the young woman to the Leskie murder and at first dismissed the ‘cold hit’ as an ‘adventitious’ (coincidental) match. However, a coroner’s investigation established that DNA from the young woman had been processed through the same laboratory at about the same time as the toddler’s clothing. The young woman had allegedly been the victim of a sexual assault involving a condom. Although laboratory personnel maintain that accidental transfer of samples between cases is impossible, it now appears almost certain that the young woman’s DNA from the outside of the condom accidentally contaminated samples from the toddler’s clothing.

“The facts of some recent cases in the United States have also raised suspicions about false cold hits due to contamination across cases. For example, in 2002, while investigating the 1969 murder of University of Michigan law student Jane Mixer, the Michigan State Police Crime Laboratory in Lansing found DNA of two men on her clothing. The profiles were searched through a database and matched two Michigan men, Gary Leiterman and John Ruelas. Police immediately suspected that Leiterman and Ruelas had been involved in the murder, but there was a problem — Ruelas was only four years old when Mixer was killed and had been living with his parents in another city. According to news accounts, police could find no link between young Ruelas and Mixer.29 That did not deter Washtenaw County Assistant Prosecutor Steven Hiller who charged Leiterman with the murder. Hiller ‘created a scenario placing a young Ruelas at the [murder] scene as a chronic nose-bleeder whose blood dropped on Mixer.’30 There is, however, another possible explanation for this ‘cold hit.’ Examination of laboratory records revealed that known samples of DNA from both Leiterman and Ruelas were being processed in the Michigan State lab on the same day as the old samples from the Mixer murder.31 Both men were being tested in connection with other cases unrelated to the Mixer murder. Although the Michigan State laboratory maintains that cross-contamination of samples across cases was impossible, it seems a very strange and unlikely coincidence that two men who, according to the prosecutor, were present when Mixer was murdered in 1969 just happened to have their DNA tested (for other cases) on the very same day as samples from the Mixer case were tested. Leiterman was nevertheless convicted of Mixer’s murder in 2005.” (emphasis added)

Footnotes for Thompson

29. Maryanne George, Murder case mystery deepens. Detroit Free Press, Jan 15, 2005.

30. According to news accounts, Hiller offered no evidence to support this theory. Liz Cobbs, Judge raises possibility evidence may have been contaminated at State Police lab, Ann Arbor News, May 11, 2005.

31. Author’s interview with Professor Dan Krane (a defense expert in the case). Also, Thersa Mask, Mixer’s dad is clear on one thing, Detroit Free Press, July 13, 2005.

Contamination is surely an unlikely event, at least in that it happens less frequently than it does not happen. Yet, which is less likely in these two cases, contamination or the involvement of the suspect identified by these cold hits? And even if improbable, how does this speak to a reasonable doubt?

Borderline situations

Suppose that a technician runs evidentiary samples and reference samples in the same batch out of laziness or ignorance. Suppose a different technician runs these samples together knowing that there is a greater chance of contamination. These two cases are distinguishable only if one knows the intent of the technicians. The second case is close to outright evidence tampering, but the similarity of the two situations implies that there is no bright line between sloppiness and outright fraud.

Frequency of Contamination

This is difficult to estimate for a variety of reasons. Donald Riley reports that some laboratories omit controls or perform them in such a way as to lessen the chances of detection. Thompson reports that many laboratories fail to record instances of contamination in a log book, despite the advice of the FBI. Some labs take the overly sanguine approach that if they detect contamination, it is not really an error. Thompson writes, “The surprise for defense lawyers who have managed to gain access to these files is how voluminous they are. Errors occur regularly.”


  • Forensic DNA contamination is a well-known phenomenon that good labs attempt to minimize, and to document when it does happen.
  • PCR-amplified DNA is one of the most serious contamination threats in a DNA forensics lab.
  • Keeping a clean DNA lab is a little like maintaining a sterile environment, only more difficult.
  • It is difficult to estimate the frequency of contamination for a variety of reasons. However, many instances have been documented.
  • Negative controls can be used to identify contamination, but they only detect contamination in blanks, not evidentiary samples.
  • Fradulent DNA forensics often takes the form of falsifying negative controls.


John M. Butler, Forensic DNA Typing (2005), 2nd ed., Elsevier.

Terri Sundquist and Joseph Bissetti

Donald Riley

Nora Rudin and Keith Inman, An Introduction to Forensic DNA Analysis, 2nd ed. (2002).

William C. Thompson 2006

William C. Thompson; Simon Ford; Travis Doom; Michael Raymer; Dan E. Krane (2003),rape

Dick Warrington Forensics April/May 2005

Dick Warrington Forensics April/May 2009


Anonymous said...

I am in no scientist but this seems to me that one should have a large enough sample to retest otherwise there is no way of knowing for sure if an error has occurred.

Anonymous said...

Thank you, Chris. As I understand it, no controls at all were performed. Did I miss something?

Looking forward to reading all the links more closely.


Chris Halkides said...


Good point. The NRC has suggested the same thing:

"What about human error?
Forensic investigators take many precautions to prevent mistakes, but human error can never be reduced to zero. The National Research Council (NRC) recommends that evidence samples be divided into several quantities soon after collection, so that if a mix-up were to occur, there would be backup samples to analyze."

And this does not even take into account the special issues with respect to LCN testing, which should be done with duplicate experiments at two stages IIRC.


Mark Waterbury said that either Stefanoni did not do the controls or she did not report them. The open letter of 19 November 2009 asks for release of the .fst files. There is a great deal of information in these files; each sample should have a separate .fst file, including the control runs. I asked a DNA forensics expert about this failure to turn over the data, and he said that not releasing these files was almost unheard of.


One Spook said...

Excellent post,Chris. I hope you will follow this up with a nexus to the Knox case, wherein you discuss the bra clasp and knife DNA evidence in light of the potential for contamination as you've outlined.

As I read about DNA evidence in this and other cases, I'm struck by how folks seem to want DNA to be a "silver bullet" --- an almost unimpeachable form of evidence. Many times I've read that DNA evidence is considered a "genetic
fingerprint" and it is often compared to traditional fingerprinting. As you have
shown, DNA collection and analysis is far more complex than simple fingerprinting. The process can fraught with problems and errors, and I think your posting is very appropriate in that it demonstrates several major
weaknesses in this complex process.

Yet, to the layman ---observer, judge, and juror alike, I believe there is a widespread misunderstanding of just how fragile this type of evidence can be.

When it is done properly, it truly is a valuable forensic tool, but one must keep in mind that it is not infallible. I think your post makes that point very well.

One Spook

Chris Halkides said...

One Spook,

To the best of my knowledge, DNA forensics is the only branch of forensics developed by scientists and subject to normal standards of scientific proofs. In these respects it might be better than fingerprinting. The first generation of DNA forensics relied upon a technique known as restriction fragment length polymorphisms (RFLPs). We are now on the third generation of forensics, one that combines plymerase chain reaction (PCR) with short tandem repeats. Bringing PCR is a mixed blessing. Clearly some of the problems I reviewed in this post are intimately related to the PCR technique.

I hope to post something on the bra clasp next then return to the knife.


Chris Halkides said...

To all,

I did not do full justice to the question of whether or not independent crime labs are independent. Here is a quote and a link with which one may start:

"The National Academy of Sciences recently published a massive study arguing for independent crime labs."

Read more at the Washington Examiner:


Chris Halkides said...

To all,

Here are a few more links on the issues of forensics reform. There are several other good articles at this site.

Shoddy forensic science has led to a major setback in a murder investigation that could close the door on efforts to bring the killer to justice. The family of murder victim Suzanne Jovin was recently informed that the DNA evidence in her case was useless because it was contaminated by a lab technician. A DNA sample collected from under Jovin’s fingernails after her 1998 murder was found to match that of the lab worker that processed the evidence, not her killer as was previously assumed.

“Often, bias is inadvertent. Information such as details of the crime, names of suspects, and the expected result can impact an analyst’s objectivity. In one study, experienced examiners were given fingerprints they had correctly identified in the past along with made up information, such as that the suspect had confessed. With the additional information, these examiners misidentified seventeen percent of the fingerprints… Ideally, all laboratories should be independent from law enforcement and prosecutorial agencies to eliminate bias from the process. Instead nearly all state forensic labs are under the jurisdictions of police departments or the attorneys general. As a result, analysts may come to see their role as part of the ‘crime fighting team’ rather than as neutral and objective agents of science. Independence helps labs become neutral environments dedicated to scientific procedures that ensure accurate and reliable testing.”


Debrah said...

These video clips that "Observer" left inside The Diva World are superb.

Dan Abrams is great....just as he was during the Lacrosse Hoax.

Chris Halkides said...

To all,

A Seattle Pos-Intelligencer article from 2004 ( made some good points. Here are five quotes:

“In the late '80s to mid-'90s, the early days of DNA ‘fingerprinting,’ it was a lot harder for forensic scientists to contaminate the tests.”

“The occasional ‘contamination event’ is inevitable, said [Ed] Blake, the California scientist, but crime labs aren't routinely disclosing those miscues.”

“Many crime labs are "stunningly ignorant: about contamination, said Janine Arvizu, an Albuquerque-based forensic scientist who has audited federal and private industry labs.
"I wish they'd step up and say, 'We need help cleaning it up,' " Arvizu said. "But they won't. It's pretty scary.”

“’Who can believe the only contamination they have is those (cases) where they can detect it? There's inevitably lots more,’ [Professor William] Thompson said.
That contention was recently confirmed by a study in the May 2004 Journal of Forensic Sciences that found that clean controls don't guarantee contaminant-free evidence.”

“Olson, who has worked in the crime lab system since 1998, said she tried not to be swayed by detectives' belief that they had a strong suspect. ‘We're all human,’ she said. ‘I tried not to let it influence me. But I can't say it never does.’”

The story involving Denise Olson concerns investigator bias and the problems of DNA mixtures. It seemed too long for a comment, but it is worth reading in its entirety.


Anonymous said...


(I wasn't sure where to put this. Please edit and place where you would like it to be if not here.)

I am posting a link to the Italian version and a very rough English translation of the Micheli report on the Guede trial/verdict.

The original 106 page report is in Italian and is posted on the Ministry of Justice website. There will be a similar report done by the trial judge for the Knox/Sollecito Trial due sometime in March.

Micheli was the judge who sentenced Guede to 30 years and was also the pre-trial judge who said there was enough evidence for Knox and Sollectio to proceed to trial.

In the report Micheli writes about some of the forensic evidence (among other pieces of evidence) presented at Guede's trial.

As I posted above, the English translation is rather rough but maybe someone will be able to make sense of the forensics included in it. It has been stated/speculated that much of the same forensics presented in the Guede trial were also used in the Knox/Sollectio pre-trial and trial.

106 page Micheli report (Italian)

106 page Micheli Report (English)


Debrah said...

This page from those links has both Italian and English.

Anonymous said...

I have seen bits and pieces of that report, but it is nice to see it all in one place. And it does seem to contain quite a bit of forensic as well as circumstantial evidence. Now if I can just get someone to explain the la mossa thing that they asked Amanda at at trial.


Anonymous said...


Thanks. I did not notice the links had both translations until your post stating such. I wish the English translation was easier to read/comprehend.

Now, if I could post links that one could click on rather than copy and paste.


Perhaps your question will be answered in the judge's report due in March.


Anonymous said...

The html format I use for posting a link is

#a href="">Go Seahawks#/a$

Substitute the #'s with < and the $ with > Copy the actual link between the " " and type whatever name for the link you want it to be clickable, as Debrah used This Page for hers.

Anonymous said...

The La Mossa comment appeared to be one of the rare moments of humor in the testimony. I was just curious as they were asking her about her gymnastic activity and one of the officers said she then proceeded with something described as la mossa (after her splits and cartwheels). The translator was having a difficult time with an adequate English equivalent.


One Spook said...

Strictly a guess, Rose, but I believe that "la mossa" (literally "the move") probably means "moves" much as we say in English that someone has "moves" as used in a flirtatious context, such as, "He has a lot of moves that he puts on women."

One Spook

Anonymous said...

I saw your added comments about your doubts of the Knife being the murder weapon. You say Knox would have cleaned her fingerprints along with the blade and there was no need to transport the Knife in the first place. I just wanted to add if Rudy saw you use this blade and you don't know what Rudy, a witness, is going to do next
that would be even more reason to get rid of the knife. Why give credibility to the witness that might turn on you. TM

Anonymous said...

One Spook,
I think you are correct on the meaning of that word, thanks.

I am still bothered about the mop and the importance Amanda gave it in her email to everyone. I tried to find a similar statement from Sollecito that was not part of his official statements, influenced or coerced by the cops. If you recall Amanda seemed to give this mop a leading role in her story and here, it appears Sollecito does the same:

From his Prison diary, first quote:
don't remember in reality at what time I ate, but certainly I ate and Amanda ate with me. The questions the agents of the Squadra Mobile me have made me to remember that that day the water pipe under to sink was detached and thing I find very suspicious, I've seen that it is not possible to so detach alone, at any rate, the fact is that it flooded half the house.

It seems we now get yet another story in the life of that pesky mop, this time someone went under his sink and detached the "trap". I even saw a picture on a website that had this U section of pipe missing posted as proof the pipe had busted. Of course they were assuming it wasn't some suspicious character that did that foul deed. Interesting to note that he said it flooded half the house, yet they appeared to be in no hurry for that mop until the next morning. Next quote: She was cleaned up and had brought me a mop in order to help me to dry the floor around the sink. The evening before I had put only rags on the floor and they were not enough.After that I cleaned up the floor and perhaps I made breakfast around
11:30-12:00 I changed clothes and we went out. She meanwhile had
spoken to me about the fact that she had found something strange at
her house. That is that she had found the front door opened, feces in the bathroom of the Italian girls and blood in their bathroom. While we came down from Corso Garibaldi she expressively demanded that I go to see in her house what had happened.

That quote almost supports her version when she was so scared she went running back to Sollecito's to tell him something bad may have happened (after mopping up a bit of water anyway).
Next quote: s soon as we arrived in the house I put aside the mop in the entrance
and I directed myself towards the other rooms in order to see what the devil had happened. Those moments I remember well because I was shaken and alarmed. I seem to have seen that Amanda had taken the mop bucket and it carried it in to another room

Ok, to paraphrase: what the devil has happened here but let me put this very important mop in a prominent resting place first and then be sure to include this mop in every statement I give about this case from now until the end of time. I am still finding the various mop/sink versions more bizarre the more I read.


Anonymous said...

TM (Would that be Tortmaster?), This knife as the murder weapon makes about as much sense to me as the importance Knox and Sollecito are giving the mop. That unfortunately doesn't prove innocence, but should certainly not be considered as proof of their guilt, in my opinion.

Anonymous said...

One thing about a mop to remember
is that it is something impossible to clean. I may be wrong but when press releases first came out in the U.S this mop thing was mentioned before AK made any statements. She may have been very conscious of this unfortunate scenario and wanted to explain it as best she could. TM

Anonymous said...

I am not sure that sticking a mop in a bucket of bleach will 'clean' it to the point where testing is useless or not, TM. What does surprise me is that I still have not found any indication that the mop was even tested, given the constant references to it boy both Knox and Sollecito.

The cellphone and computer activity of Knox and Sollecito the morning after the murder are very telling in contrast to the many statements they have made giving a timeline of what they did that morning. If I recall, Amanda states she got up about 10AM to go back to her flat for a shower and to retrieve the aforementioned mop. Sollecito remembers her leaving and going back to sleep, then her coming back around 11AM, afterwards they were mopping the kitchen and having breakfast.
The computer activity however shows downloading a media file a few minutes before 6AM and the cell phone activity shows both their cell phones were turned on about the same time. This would seem to me they were indeed up very early that morning and for some reason are trying to cover for about a 3 to 4 hour gap. I don't recall seeing an explanation from either of them about this but it is possible I have missed something.


Chris Halkides said...


The issue of the activity at 6 AM has always bothered me also. However, one of Sollecito's hard drives was burned up, and the other one had information inadvertantly erased. So, the assertion about computer activity at 6 AM has to be judged against their demonstrated incompetence. I am no computer jock, though, and I have no idea how one might see activity at 6 AM that is not really there. Could there have been an automatic download? Just a WAG on my part.


Chris Halkides said...


My previous phrase wit respect to computer information, "their demonstrated incompetence," refers to the police. Here are a couple of links with respect to phone records:

The second of the two links is to the James Randi educational forum. I do not recommend posting there; the discussion is people shouting and playing "gotcha."


Chris Halkides said...


Here is another post on the plumbing:


Chris Halkides said...

To all,

Here is Frank Sfarzo's summary of Amanda Knox's testimony:


Anonymous said...

Frank does an excellent job touting the innocence of Amanda Knox. In the plumber story he doesn't really give you the timing of things, nor does he point out the many versions of the broken pipe, accidentally spilled water, flooded half the house, fish or pasta, and very important mop information. From what I recall, the plumber had been out and fixed the problem a week or so before the murder. I have not seen it confirmed it was even the same issue they had the first time. It does provide them with a nice explanation for the mop, however, once they got their stories down pat and if there were not so many inconsistent versions of their statements and so much emphasis on the movements of the mop, I would pay the whole mop issue no mind at all.

As far as the summary of her testimony goes, I agree she gave an amazing performance, one that Frank seems enamored of.


Chris Halkides said...

Here is another case of contamination from Australia:


Unknown said...


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