I have followed the Amanda Knox case over its course, and was recently able to attend a talk given by Prof. Greg Hampikian of Boise State University on the subject. Prof. Hampikian is also Director of the Idaho Innocence Project and an internationally recognized authority on DNA forensics. Prof. Hampikian advised the Amanda Knox legal team on DNA issues.
After the dust had settled, I felt compelled to write a brief summary of the case based upon my own knowledge of the case combined with information from Prof. Hampikian’s presentation – just to try to put it all into perspective. That summary follows.
What Really Happened in the Amanda Knox Case?
Meredith Kercher Murder victim, British student
Amanda Knox Accused murderer, American student, one of . Meredith’s roommates
Raffaele Sollecito Accused murderer, Italian student, Amanda’s . recent boyfriend
Rudy Guede Accused murderer, drifter and petty criminal . from the Ivory Coast
Diya Lumumba Tavern owner in Perugia, Italy
Giuliano Mignini Prosecutor
Meredith Kercher was found murdered in her apartment in Perugia, Italy on Nov. 2, 2007. She had stab wounds under her chin, and her throat had been deeply cut (cause of death).
Amanda Knox was one of Meredith’s roommates. They and a few other girls rented a house in Perugia. Two weeks before the murder, Amanda had begun dating Raffaele Sollecito, also a student, who lived within a 5 minute walk from Amanda’s apartment. Amanda occasionally worked in a local tavern owned by Diya Lumumba.
On Nov. 6, 2007, Amanda Knox, Raffaele Sollecito, and Diya Lumumba were arrested in connection with the murder. Lumumba had been implicated in statements made by Amanda. However Lumumba had an airtight alibi – he was tending his tavern at the time of the murder, as attested by numerous witnesses. Lumumba was released without charge on Nov. 20 for lack of evidence. Rudy Guede had fled to Germany, and could not be immediately taken into custody.
The Italian evidence technicians actually did a very good job of collecting evidence – with a few exceptions noted later. Guede’s DNA was all over the place, in large amounts. It was in the bloody handprint on a wall, it was on Meredith’s purse, on her body and in her vagina. None of Amanda’s DNA was found at the crime scene, zero, and there never would be. None of Raffaele’s DNA was found initially.
In Italy, rents are paid in cash. Meredith Kercher was found murdered on the second day of the month. The day after the murder, Rudy Guede was observed spending money he hadn’t had before. Shortly after the murder, Guede fled to Germany.
Sounds pretty “open & shut”, doesn’t it? Clearly, Guede robbed Meredith for the rent money, molested her, killed her, and fled to Germany. Not so fast. Italian prosecutor Guiliano Mignini believed that Amanda and Raffaele were not “acting normally” subsequent to the murder, and solely on that belief, he insisted on prosecuting Amanda and Rafaelle for the murder. However, he had one very big problem – he didn’t have any evidence.
On Dec. 6, 2007 Guede was extradited from Germany, and jailed in Italy. He was granted a ‘fast track’ trial, and was convicted of murder on Oct. 28, 2008. He was sentenced to 30 years in prison, but the sentence was subsequently reduced to 16 years on appeal on Dec. 22, 2009. Note that in criminal justice systems, it’s common practice for a convicted person to have his/her sentence reduced for agreeing to testify against others, and this frequently results in false testimony.
Since the prosecutor had no evidence against Amanda and Raffaele, with the exception of Guede’s “snitch” testimony, evidence technicians went back and again searched Meredith’s apartment 7 weeks after the murder. Meredith’s bra had been torn from her body, and under a dirty rug, they found the clasp from that bra. A minute amount of Raffaele’s DNA was found on a corner of the clasp. The technicians also went back to Raffaele’s apartment, and in the kitchen knife drawer, found a large knife that had a minute amount of Amanda’s DNA on the handle and a minute amount of Meredith’s DNA on the blade. The Italian authorities claimed that the knife looked like it had been “carefully cleaned”.
On Oct. 28, 2008, Amanda and Raffaele were indicted on murder charges. Their trial began June 16, 2009. On Dec. 4, 2009 Amanda and Raffaele were found guilty. Amanda was sentenced to 26 years in prison and Raffaele to 25 years in prison. The only physical evidence in the case was the DNA on the knife blade and handle, and on the bra clasp.
On Nov. 4, 2010 an appeals court trial began for Amanda and Raffaele. On Dec. 16, 2010, Italy’s highest criminal court upheld Guede’s conviction and 16 year sentence. It’s at this point that Prof. Greg Hampikian, one of the world’s preeminent forensic DNA experts, became interested in the case while on a trip to London, and agreed to work on the case pro bono. Prof. Hampikian is with Boise State University, and is also the Director of the Idaho Innocence Project.
Before we go further in understanding the case, we need to have an understanding of the mechanism of DNA transfer. Detectable DNA transfers can be placed into one of three categories:
Primary – You touch something, bleed on something, or get your saliva on something, and your DNA is left on the object
Secondary – Somebody, or some object, touches the object that you have previously deposited your DNA on, and your DNA will be deposited on that person or object.
Tertiary – If the person, or object, who has your (secondary) DNA on it, touches another object, your DNA will then be deposited on that new object. Tertiary transfer DNA deposits can be detectable, but beyond that (quaternary), they are realistically not.
Quite logically, as transfers progress from primary to secondary to tertiary, the amount of DNA in the deposited sample gets to be less and less. The only transfer that can logically, and legally, implicate someone is a ‘primary’ transfer. For this reason, forensic DNA analysis places limits on the amount of DNA in a sample below which it cannot be considered a primary transfer; otherwise, it’s not possible to say where the DNA came from.
When a DNA sample is analyzed, the results are recorded on an “electropherogram”. A typical electropherogram looks like this:
The horizontal axis is scaled in units of “molecular weight”. The vertical axis is scaled in units of “relative fluorescence units” (RFU’s). Molecular weight identifies the specific DNA molecules in the sample. The RFU’s identify the amount of that particular DNA molecule in that sample. On this chart, the molecules that are present in an amount greater than 150 RFU’s are identified as valid DNA components in this sample, so they are marked with a vertical gray line and a box below the axis showing the corresponding molecular weight. Any molecules that are present in amounts less than 150 RFU’s cannot be considered as resulting from a ‘primary transfer’, and it’s not possible to tell where that DNA came from. The RFU “cutoff” used by the FBI is actually 200 RFU’s, so a 150 RFU cutoff would be even more inclusive.
In the Amanda Knox case, in order to determine Meredith’s DNA on the knife blade, it was necessary for the DNA analysts to go down to an RFU level of 15 – one tenth of the cutoff of the most inclusive DNA analysis. This could not have resulted from a primary transfer; that is, the knife blade could not have been in direct contact with Meredith, much less her blood. The Italian authorities had claimed that the knife had been “carefully cleaned”, but we’ll come to that later.
The data was similar for Raffaele’s DNA on the bra clasp, meaning that Raffaele could not have directly touched it.
So how did Meredith’s DNA get on the knife blade, and Amanda’s on the knife handle, and Rafaelle’s on the bra clasp? With the DNA levels detected, it had to be secondary or tertiary transfer.
a) Meredith and Amanda were roommates and friends. Amanda certainly had Meredith’s primary and secondary DNA on her. All she had to do was to be cooking in Raffaele’s apartment kitchen, and she would have left her own DNA on the knife handle, and could certainly have left Meredith’s DNA on the blade.
b) Raffaele and Amanda were dating, and consequently, he knew Meredith, and had contact with her. All he had to do was to shake hands with Meredith, and she would have his primary DNA on her, and she would transfer his secondary DNA to her bra clasp.
c) A combination of two things. To begin with, Amanda and Raffaele were allowed back into the apartment after the initial evidence collection – not a good idea. While viewing video of the Italian evidence technicians collecting the evidence, Prof. Hampikian noticed that they were not changing their gloves between handling different pieces of evidence. This creates a situation for secondary or tertiary transfer both in the initial evidence collection procedure and subsequent to Amanda and Raffaele being allowed back into the apartment.
Recall that the Italian authorities had claimed that the knife had been “carefully cleaned”. When the appeals-court-appointed Italian DNA experts examined the knife microscopically, they found that it was coated with potato starch. So much for careful cleaning.
Prof. Hampikian advised Amanda’s legal team about the DNA issues. The Italian court appointed two independent, Italian DNA experts to review the evidence, and their conclusion was that the DNA evidence presented at trial was not scientifically supportable, and consequently not valid.
The end result? Amanda is back in Seattle with her family.
In retrospect, it is this editor’s opinion that this was all the result of a “rogue” prosecutor. Just a little bit of research into Mr. Mignini’s background will reveal that it is not unblemished.