Innocent Man Charged With Murder Because His DNA Was Found On The Fingernails Of Victim, Whom He Had Never Met
from the DNA-is-formidable,-not-infallible dept
The forensic use of DNA is rightly regarded as one of the most reliable ways of establishing the identity of someone who was present at a crime scene. As technology has advanced, it is possible to use extremely small traces of genetic material to identify people. One possibility that has so far received little attention is that the DNA of someone might be transferred accidentally to a murder victim's body, say, even though the former person had absolutely nothing to do with the latter's death, and maybe had never even met him or her. The Marshall Project has a fascinating and important report on just such a case.
Back in 2012, a group of men broke into the Silicon Valley home of a 66-year-old investor, tied him up, blindfolded him, and gagged him with duct tape. The duct tape caused him to suffocate, turning a robbery into a murder. Some DNA found on the victim's fingernails matched that of a homeless man, who was well-known to local police. It seemed an open-and-shut case -- even the alleged murderer, who had memory problems, admitted he might have done it, given this apparently incontrovertible proof. Fortunately, his lawyer was diligent in checking everything about her client in the hope of at least mitigating his punishment. As she examined his medical records, she discovered the following:
The medical records showed that [the accused] Anderson was also a regular in county hospitals. Most recently, he had arrived in an ambulance to Valley Medical Center, where he was declared inebriated nearly to the point of unconsciousness. Blood alcohol tests indicated he had consumed the equivalent of 21 beers. He spent the night detoxing. The next morning he was discharged, somewhat more sober.
That night her client had been in hospital was when the murder had been committed. Further research confirmed that he could not have been on the crime scene, and also that he had never met the victim. The question then became: how had his DNA -- for there was no doubt it was his -- ended up on the fingernails of a murdered man?
The connection was found in the paramedics who had responded to the discovery of the murder victim. It turned out that earlier that day they had taken the innocent man accused of the murder to Valley Medical Center after he had collapsed drunk in a supermarket. Somehow, improbable as it might seem, they had transferred his DNA onto the murder victim, where it was later discovered by the forensic scientists.
The Marshall Project article goes into much more detail about the case and the history of using DNA to solve crimes -- it's well-worth reading. It highlights two crucial facts that need to be taken into account when DNA is used as evidence, especially for serious crimes carrying heavy penalties. One is that we all leave our DNA everywhere:
An average person may shed upward of 50 million skin cells a day. Attorney Erin Murphy, author of "Inside the Cell," a book about forensic DNA, has calculated that in two minutes the average person sheds enough skin cells to cover a football field. We also spew saliva, which is packed with DNA. If we stand still and talk for 30 seconds, our DNA may be found more than a yard away. With a forceful sneeze, it might land on a nearby wall.
To find out the prevalence of DNA in the world, a group of Dutch researchers tested 105 public items -- escalator rails, public toilet door handles, shopping basket handles, coins. Ninety-one percent bore human DNA, sometimes from half a dozen people. Even items intimate to us -- the armpits of our shirts, say -- can bear other people's DNA, they found.
The other fact is that contamination of key DNA samples by those investigating a crime is the rule, not the exception:
A 2016 study by Gill, the British forensic researcher, found DNA on three-quarters of crime scene tools he tested, including cameras, measuring tapes, and gloves. Those items can pick up DNA at one scene and move it to the next.
Once it arrives in the lab, the risk continues: One set of researchers found stray DNA in even the cleanest parts of their lab. Worried that the very case files they worked on could be a source of contamination, they tested 20. Seventy-five percent held the DNA of people who hadn't handled the file.
As the article emphasizes, DNA is indeed an incredibly powerful forensic tool, which has helped convict the guilty, as well as exonerate the innocent. But it is not infallible. The question is: how many other people have been wrongly charged, convicted and punished because of stray DNA?
Follow me @glynmoody on Twitter or identi.ca, and +glynmoody on Google+.
Thank you for reading this Techdirt post. With so many things competing for everyone’s attention these days, we really appreciate you giving us your time. We work hard every day to put quality content out there for our community.
Techdirt is one of the few remaining truly independent media outlets. We do not have a giant corporation behind us, and we rely heavily on our community to support us, in an age when advertisers are increasingly uninterested in sponsoring small, independent sites — especially a site like ours that is unwilling to pull punches in its reporting and analysis.
While other websites have resorted to paywalls, registration requirements, and increasingly annoying/intrusive advertising, we have always kept Techdirt open and available to anyone. But in order to continue doing so, we need your support. We offer a variety of ways for our readers to support us, from direct donations to special subscriptions and cool merchandise — and every little bit helps. Thank you.
–The Techdirt Team
Filed Under: contamination, dna, evidence, forensics
Companies: marshall project
Reader Comments
Subscribe: RSS
View by: Time | Thread
DNA is also extremely easy to plant.
[ link to this | view in chronology ]
Re: DNA is also extremely easy to plant.
Apropos the recent cracking of a cold case?
[ link to this | view in chronology ]
I did my first programming with punch cards, back when it was still common to hear the claim "Computers don't make mistakes!"
Despite the astronomically high improbabilities claimed for false DNA matches, gosh, I hear of a lot of false matches. They're for much the same reasons as computers: Procedural errors at the lab. Data entry errors. And just plain bad data.
That includes the Phantom of Heilbronn: An unknown female serial killer whose existence was inferred from DNA evidence found at numerous crime scenes in Austria, France and Germany from 1993 to 2009.
Investigators later concluded that the DNA belonged to a woman who worked at the factory where the cotton swabs used at all the crime scenes were made.
[ link to this | view in chronology ]
Re:
May she one day slip up and get caught.
[ link to this | view in chronology ]
Re:
[ link to this | view in chronology ]
Planting DNA
[ link to this | view in chronology ]
[ link to this | view in chronology ]
Re:
The case above involves an entirely different problem. So-called professionals, including paramedics and lab analysts, are routinely sloppy in transferring DNA from one person to another. Better training and procedures would help, but jurisprudence has always been a hit-or-miss affair and only in Wonderland will it ever be different.
[ link to this | view in chronology ]
Minimum amount
On the nail is not the same as skin found under the nail from scratching and resistance. We can extract DNA from very very very very very very tiny samples so maybe we need a minimum amount of DNA present to ensure it is not accidental or environmental transfer?
[ link to this | view in chronology ]
Nothing new
[ link to this | view in chronology ]
DNA from blood, semen, saliva is really hard to claim came from someone else or was planted.
Touch DNA, even the Dr. (iirc) who was involved in showing how it worked said it can't be the be all end all because everyone sheds.
DNA is just magic these days.
If they find yours, the jury knows you did it.
If they finally test yours, you get off of death row.
No one has explained how everyone sheds cells differently & how in testing they showed items never touched by a subject having their DNA on it from others being in the same area.
Everyone wanted a tool that could take the tiniest scrap of DNA and show us the murderer before the 2nd commercial break.
The problem is that many times the investigation stops once the DNA matches, thankfully for this man he had an airtight alibi once they were willing to look at it.
Everything they imagined up until that point about his involvement would have convicted him & been taken as truth.
Tools are just tools, not perfect magic.
They can be misused & abused, we can not allow people to think the science is perfect. Look at all of the labs having to toss convictions b/c they finally decided maybe they should look at their labs & notice the missing drugs not to mention one person doing testing at like 7x the rate of other top labs.
[ link to this | view in chronology ]
[ link to this | view in chronology ]
Re: Reasonable Doubt
[ link to this | view in chronology ]
Re: Last I heard fingerprints are no longer infallible
[ link to this | view in chronology ]
Waitin' for the Knock
[ link to this | view in chronology ]
Simple solution
If DNA is used to locate a suspect then it cannot be used in evidence.
[ link to this | view in chronology ]
The Fallibility of DNA
[ link to this | view in chronology ]
Re: The Fallibility of DNA
[ link to this | view in chronology ]
[ link to this | view in chronology ]
Read the details, this guy lied to you, he's not innocent
[ link to this | view in chronology ]