Hi everyone,
Here is an article about DNA transfer and its implications for forensic investigations.
http://www.sciencedaily.com/releases/2015/10/151028133944.htm*********************
If your DNA is found on a weapon or at a crime scene, does that make you guilty?
A judge or jury might think so, but a new study from the University of Indianapolis shows that secondary transfer of human DNA through intermediary contact is far more common than previously thought, a finding that could have serious repercussions for medical science and the criminal justice system.
..advances in the field now make it possible to produce a complete genetic profile of a suspect from just a few cells left behind -- so-called "touch DNA." The emerging concern, long considered a theoretical risk but only now systematically confirmed by the UIndy study, is that the presence of those cells does not prove that the person actually visited the scene or directly touched the object in question. The DNA easily could have been transferred by other means.
The experiment designed by Cale and Earll asked pairs of volunteers to shake hands for two minutes, after which they handled knives that were later swabbed for DNA samples. In 85 percent of the cases, DNA from the person who did not directly touch the knife was transferred in sufficient quantity to produce a profile. In one-fifth of the samples, that person was identified as the main or only contributor of DNA to the potential weapon, despite never having touched it.
"It's scary," said Cale, who is continuing her master's thesis project at UIndy. "Analysts need to be aware that this can happen, and they need to be able to go into court and effectively present this evidence. They need to school the jury and the judge that there are other explanations for this DNA to be there."
In a 2013 California case, a man was arrested and held for months on a murder charge after his DNA was found on a homicide victim. The charges were dropped after it was determined that the DNA probably was transferred to the victim by paramedics who had come into contact with each of them on separate emergency runs.
...sometimes the only evidence they have in a case is DNA, and this emphasizes that we need to interpret the entirety of a case," said Latham, known internationally for her work as a forensic anthropologist. "Even everyday people on a jury need to understand that DNA is not this magic bullet, that it needs to be interpreted just like any piece of evidence."
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Cheers.
Sriram
