There is no doubt DNA results have been cussed by RDI! Its this single item of evidence (multiple items really , since it was found in multiple places) that has shot the RDI case down.
Sigh, here we go again.
HOTYH, as BOESP has said, this has been discussed a great many times:
[ame="http://www.websleuths.com/forums/showthread.php?t=90751"]The DNA - for RDI - Websleuths Crime Sleuthing Community[/ame]
[ame="http://www.websleuths.com/forums/showthread.php?t=88970"]Any DNA experts agree w/RDI that transfer is more likely than intruder? - Websleuths Crime Sleuthing Community[/ame]
[ame="http://www.websleuths.com/forums/showthread.php?t=67357"]I talk with a DNA expert - Websleuths Crime Sleuthing Community[/ame]
[ame="http://www.websleuths.com/forums/showthread.php?t=42762"]Serious DNA discussion - Websleuths Crime Sleuthing Community[/ame]
[ame="http://www.websleuths.com/forums/showthread.php?t=67181"]POLL: Has the DNA evidence changed your theory on who killed Jonbenet? - Websleuths Crime Sleuthing Community[/ame]
[ame="http://www.websleuths.com/forums/showthread.php?t=90999"]DNA Revisited - Websleuths Crime Sleuthing Community[/ame]
(Just to name a few)
DNA obtained from skin cells alone, in the absence of other exculpatory evidence, should not in this, or any case, be used to clear anyone without proper consideration of inculpatory evidence.
DNA obtained from skin cells alone, in the absence of corroborating evidence, would not in this, or any case (barring exceptional circumstances), be sufficient to successfully prosecute anyone.
DNA obtained from skin cells alone, has only approximately the same probative value as fiber evidence. I say this primarily because both are easily transferable and offer the potential for “innocent” explanations via a number of transfer mechanisms including secondary transfer.
This is completely unlike DNA obtained from bodily fluids for which “innocent” explanations are very difficult to come by. Essentially you are down to human error or contamination as the only alternative to guilt.
What are the possible explanations for the DNA in the Ramsey case?
(Not an exhaustive list.)
Intruder left behind skin cells via primary transfer during the assault and murder of JBR.
Someone known to the Ramseys left behind skin cells while in some way participating in the crime directly or in the staging of the crime.
Human error (such as mistyping DNA due to complex mixtures and perhaps low sample size.)
Contamination.
Innocent transfer.
Secondary and tertiary transfer.
Human error:
· The police could find no link between the schoolboy and the evidence—a car bomb planted in Lisburn, Northern Ireland—on which his DNA profile was supposedly found. Unless the boy has a secret life as a bomb-building terrorist that police failed to detect, this appears to be yet another false cold hit. Perhaps the match could be due to incidental transfer of the tiny quantities of DNA detected by the test. Professor Dan Krane, who testified for the defense in the Omagh case, speculated that the boy might have shaken hands with someone who later shook the hand of the bomb maker. In my view a more likely explanation is that this was a coincidental match that followed mistyping of a difficult evidentiary sample.
http://www.councilforresponsiblegenetics.org/pageDocuments/H4T5EOYUZI.pdf
· The list of DNA testing errors, uncovered through public-records requests and interviews with defense attorneys and experts, offers an unusual glimpse into what can go wrong. Crime labs across the country are struggling with similar problems but documented evidence has been hard to come by.
The State Patrol cases reveal that the technology has an Achilles' heel: human error.
Forensic scientists tainted tests with their own DNA in eight of the 23 cases. They made mistakes in six others, from throwing out evidence swabs to misreading results, fingering the wrong rape suspect. Tests were contaminated by DNA from unrelated cases in three examinations, and between evidence in the same case in another. The source of contamination in five other tests is unknown.
…
Crime lab officials here and elsewhere don't like to talk about the fact that the same test that can link someone to a crime scene with a few minuscule cells left on a doorknob can also be contaminated by a passing sneeze. Or that DNA tests are only as reliable as the humans doing them -- a troubling prospect when dealing with evidence that has the power to exonerate suspects or imprison them for life.
"The amazing thing is how many screw-ups they have for a technique that they go into court and say is infallible," said William C. Thompson, a forensic expert and professor of criminology and law at the University of California-Irvine, who reviewed the incidents at the request of the P-I.
"What we're seeing in these 23 cases is really the tip of the iceberg."
That's because the lab is only catching obvious cases that likely signal more widespread problems, Thompson said.
http://www.seattlepi.com/local/183007_crimelab22.html
Innocent transfer and contamination:
· Highly sensitive tests require a great deal of care in evidence collection, handling and storage.
What precautions were taken in the Ramsey case, or any case in the 90’s, when the potential for contamination and cross-contamination involving skin cells was not known?
This is from a recent interview between Evidence Technology Magazine and Joe Minor-Technical DNA Manager & Special Agent-Forensic Scientist Supervisor, Tennessee Bureau of Investigation:
EVIDENCE TECHNOLOGY: When you teach classes for crime-scene investigators, what are some of the key points in DNA collection that you cover?
MINOR: I talk to them about basic concepts, like proper recognition and preservation of the evidence. We discuss the fundamentals of packaging biological evidence and how that should be packaged in breathable containers. And everything needs to be packaged separately. Even if they think that it is the victim’s clothes and it is all the victim’s blood and it wouldn’t hurt to package a few of those similar items together… I say: Stop and think about that. Don’t do it. Package everything separately so there is no cross-transfer.
…
EVIDENCE TECHNOLOGY: The technology you are using is getting very sensitive, isn’t it?
MINOR: Yes—which brings up another thing that I tell folks about changing their gloves frequently to prevent cross-contamination. It is pretty well understood that when you are at a scene collecting bloody items, you don’t want to touch something, get blood on the gloves, and then handle another item. Everybody knows that. But now we need to start thinking about skin cells. If you are wearing a glove and you handle something that may have been handled by somebody else, you may need to think about changing gloves before you touch the next item. As a matter of fact, if you put on a pair of clean gloves and you inadvertently bring your finger up and scratch your face or nose, then your skin cells are going to be on that glove, and that can go to the next item you touch, as well.
EVIDENCE TECHNOLOGY: How about fingerprint brushes? Can they cause cross-contamination of DNA?
MINOR: Well, that’s a very good question. As a matter of fact, one point in our laboratory’s policy states that items that have been processed for latent prints will not be examined for touch DNA. Most people are not using disposable brushes, from what we understand. The problem with that is going to be if you dust with a brush that has dusted blood samples from a previous case and it gets transferred to an item. If you are lucky enough to get a DNA profile from that item, it could be very problematic because then you have a profile that might not match the suspect because it really came from another crime.
http://www.evidencemagazine.com/index.php?option=com_content&task=view&id=160&Itemid=9
and…
· Trace DNA Precautions
By The Colorado Bureau of Investigation Laboratories
Have you ever thought about what happens to objects when you breathe on them, cough or sneeze near them, talk over them, or even adjust your glasses or wipe your brow while wearing gloves? All of these offer the potential to deposit your DNA on surfaces, usually unknowingly!
Remember when we used to wear gloves and masks to avoid getting something from a body or scene? Technology has changed the way we need to do our business.
Our intent is to provide a brief overview of what can happen at scenes, in a lab, morgue or autopsy room, and what information can be obtained from DNA as analyzed at the Colorado Bureau of Investigation.
What are some precautions we can all take to minimize this “trace DNA” from ourselves? This is the classic two-edged sword. We have the sensitivity to get identifiable DNA from someone’s finger touching a light switch or doorknob (such as a perpetrator); however, this same sensitivity can allow our own DNA to be found during an analysis!
Since we are analyzing small amounts of DNA (125 cells may be adequate to get a full profile), there is also the potential of removing DNA from an item that may have significance to the case.
Let’s address DNA concerns at the scene, in the lab, morgue or autopsy room and finally the information we can obtain from DNA analysis.
Scene:
The weapon such as the grip of a firearm, the trigger of a firearm, or the handle of a knife may have DNA from the person who handled that weapon.
The body of the deceased may have DNA from someone who has manually strangled the victim. A ligature used to bind or strangle may contain DNA.
Clothing items may contain DNA of someone who has handled the clothing of the deceased.
Skin touched in the process of moving a victim in some fashion or dressing or undressing a victim may have foreign DNA.
A suspect (or anyone) may also leave DNA if they happen to cough sneeze, or spit accidentally (while talking) over or on the deceased. The doorknob used to enter and exit the room or other objects that may be present in the path from the entry way to the body.
Morgue, autopsy room, or lab:
The items mentioned above need to be handled with caution if they do end up in one of these places, especially the clothing items. Remember the removal of DNA is as significant as the addition of your DNA to an object.
We need to think about the potential for contamination from previous deceased, autopsies, or evidence; even scissors that are used to cut clothing from one body may transfer DNA to a second body or object if not cleaned.
http://coloradocoroners.org/newsletters/summer2007.pdf
Secondary and Tertiary Transfer
· Transfer of DNA is seen with variable degrees of efficiency in each of the two types of transfer experiments conducted. In most cases the transferred DNA was a lower concentration than the DNA of the individual to whom it was transferred, however, this was not observed in all instances.
In the experiments involving a kiss to the face, DNA or cells containing DNA were transferred b a kiss to an individual’s face and then to a glove in all of the experiments fun in this study.
In the experiments involving transfer of DNA via a towel, DNA or cells containing DNA were transferred to a towel, then to an individual’s face and then to a glove in all experiments with one of the towels and in none of the experiments with the other towel. In each of these sets of experiments the towel was exposed to the individuals DNA from only one face washing and drying. Larger quantities of DNA would be expected to be deposited on the towel from multiple uses of the towel.
http://www.bioforensics.com/conference04/Transfer/Taylor&Johnson%20Study.pdf
And, of course, your own thread, HOTYH, offers a number of “innocent” explanations regarding the DNA in this case:
[ame="http://www.websleuths.com/forums/showthread.php?t=91175"]...and perhaps an innocent explanation... - Websleuths Crime Sleuthing Community[/ame]
