Beware Accidental DNA!
- Roy Catchpole
- May 25, 2020
- 8 min read
Updated: Jul 1, 2020
Readers of this post may find the following information re DNA transfer useful in demonstrating their innocence or the innocence of those falsely accused whom they are supporting.
“We should be careful to get out of an experience only the knowledge that is in it – and stop there; lest we be like the cat that sits down on a hot stove-lid. She will never sit down on a hot stove lid again – and that is well; but also she will never sit down on a cold one anymore.” Mark twain.
When the DNA results came back, this innocent man thought he may have committed the murder, although he knew he had not.
Lukis Anderson
When a San Jose man charged with murdering a Monte Sereno millionaire was suddenly freed in May 2013, prosecutors acknowledged he had an airtight alibi - he was drunk and unconscious at a hospital when the victim was killed in his mansion miles away.
But a mystery remained: How did the DNA of 26-year-old Lukis, who was so drunk his blood alcohol content was five times the legal limit - end up on the fingernails of the murdered billionaire Raveesh Kumra?
Lukis Anderson was a homeless alcoholic, 26 years old with a long record of petty crime behind him. He spent most days begging on the street in downtown San Jose.
“Well, yeah. I do like a drink,” he told his defence counsel as they sat in the interrogation-room at the Santa Clara County, California Jail. “Sometimes it gets so bad I just black out, so it’s possible I just don’t remember what I did. Maybe I did do it!”
His publicly-funded counsel quietened him down. It looked bad. But that kind of statement, if he made it in court, could easily see him off to death row and the chair. But it did not look good for Lukis.
The Murder Scene
There was no doubt that Raveesh Kumra, a 66-year-old investor, had been murdered. Suffocated by the duct-tape that had been used by his killers to keep him quiet. Raveesh lived in Monte Sereno, many miles, and social classes away from Anderson.
News reports recorded the known facts:
Around midnight on November 29, 2012, a group of men had broken into Kumra's 7,000-square-foot mansion. The victim was discovered watching CNN in the living room. His killers tied him, blindfolded him, and gagged him with duct tape. They found his companion, Harinder, asleep in an upstairs bedroom, hit her on the mouth, and tied her up next to Raveesh. Then they ransacked the house for cash and jewellery.
After the ordeal, Harinder, still blindfolded, felt her way to a kitchen phone and called 911. Police arrived, then an ambulance. One of the paramedics declared Raveesh dead. The coroner would later conclude that he had been suffocated by the duct-tape.
Three and a half weeks later, the police arrested Anderson.
The Apparently Damning Evidence
Lukis’s DNA had been found on the murder victim’s fingernails.
Police investigators, working from the presence of the DNA, put together the likely scenario. They emerged with the idea that the men had struggled as Anderson tied up his victim, transferring his DNA directly to the victim’s fingernails.
But as they looked at the DNA results, Anderson’s counsel was unable to find convincing evidence that her client committed the murder, or even that he was present at the scene. Meanwhile Lukis himself, failing to recall any of this event, struggled to make sense of a crime he had no memory of committing.
"Nah, nah, nah. I don't do things like that," he told her. "But maybe I did."
“Lukis”, she said, “Let's just hit the pause button till we work through the evidence to really see what happened."
Five months passed. Lukis languished in jail. No-one could work it out. But eventually it was discovered that Lukis Anderson's DNA had found its way onto the fingernails of a dead man he had never even met.
What actually happened.
The solution to the quandary was quite simple. The paramedics who attended the murder scene had gone on a second call. To Lukis Anderson. This resulted in the inadvertent DNA transfer.
The question whether the paramedics had thoroughly cleaned themselves between the two calls remains unanswered by the authorities. Citing the unique nature of the two incidents, a representative said, "This is not going to happen on a regular basis.
Roland van Oorschot
It was the publication of an academic paper by forensic scientist Roland van Oorschot that launched forensic science from its 1980’s infancy into adulthood.
His paper ‘DNA Fingerprints from Fingerprints’ (1997) changed everything.
DNA, it was discovered could be found not just from bodily fluids but from tiny traces left by a single touch.
This was Aladdin’s Cave for investigators, and for forensic science.
Everyone leaves a trail of DNA everywhere they go. Everyone can be identified from their DNA trace. The crock of gold at the end of the investigative rainbow.
However, in their enthusiasm to raid the crock of gold – like Mark Twain’s hot-stove-sitting cat who will never sit on a cold stove – investigators failed to look at the other possibilities. Van Oorschot's paper also contained a vital – but ignored observation:
Some people's DNA appeared on things that they had never touched.
Since then, van Oorschot's lab, investigating ‘secondary transfer’ have learned that once it is out in the world, DNA does not always stay where it is deposited.
In one of his lab’s experiments, The Complexities of DNA Transfer During a Social Setting he comments,
“…Here we consider the effects of unstructured social interactions on the transfer of touch DNA. Unscripted social exchanges of three individuals having a drink together while sitting at a table were video recorded and DNA samples were collected and profiled from all relevant items touched during each sitting. Attempts were made to analyse when and how DNA was transferred from one object to another. The analyses demonstrate that simple minor everyday interactions involving only a few items in some instances lead to detectable DNA being transferred among individuals and objects without them having contacted each other through secondary and further transfer. Transfer was also observed to be bi-directional. Furthermore, DNA of unknown source on hands or objects can be transferred and interfere with the interpretation of profiles generated from targeted touched surfaces. This study provides further insight into the transfer of DNA that may be useful when considering the likelihood of alternate scenarios of how a DNA sample got to where it was found.”
Volunteers sat at a table and shared a jug of juice. After 20 minutes of chatting and sipping, swabs were deployed on their hands, the chairs, the table, the jug, and the juice glasses, then tested for genetic material. Although the volunteers never touched each other, 50 percent wound up with another's DNA on their hand. A third of the glasses bore the DNA of volunteers who did not touch or drink from them.
“The simple reality is that the interpretation of forensic evidence is not always based on scientific studies to determine its validity. This is a serious problem. Although research has been done in some disciplines, there is a notable dearth of peer-reviewed, published studies establishing the scientific bases and validity of many forensic methods.” Professor Allan Jamieson. http://www.theforensicinstitute.com/news-articles/research
Direct and Indirect Transfer
The cells from an individual containing DNA can be found on an item through direct or indirect transfer. Direct transfer occurs by a person actually touching the item. Indirect, or secondary, transfer occurs when cells from an individual end up on an item by being carried on an intermediate person or object. It is no different from dirt, oil, bacteria, or any one of the innumerable things that get moved around unconsciously and inadvertently by being transferred from person to person or person to object, or object to person.
We no longer speculate how many angels could dance on the head of a pin. We can count the 10,000+ cells that do actually live their lives on a pinhead. These tiny, invisible organisms are easily transferred, and there are many ways this can happen.
In criminal cases, it can be of the greatest importance to understand how DNA that could have come from a suspect actually came to be on an item. Frequently, the issue is the last handler of the item, such as a weapon or item of clothing.
Research today plays an essential and influential role in underpinning a scientific opinion. Bearing this in mind, a review of the scientific literature on DNA transfer in 2007 concluded that,
“… the literature so far indicates that:
1. Where there is a known single habitual wearer, that person tends to be detected as the major source of DNA on a garment; minor profiles may also be detected from individuals with whom the habitual wearer has had close contact as well as from unknown sources.
2. The examination of evidence for handler DNA can reveal DNA of people who have, or have not, handled the item; the stronger profile may, or may not, be the person who last handled the item; An inference of direct contact between an individual and the item may or may not be supportable, depending on the circumstances of the case.”
In other words, they did not know enough to make any sensible scientific judgements as to how DNA came to be on an item.
Example of secondary DNA transfer.
If two individuals shake hands, then one person handles a knife, DNA from the first person may transfer to the second during a handshake, and then is deposited on the knife when the second person touches it.
Primary DNA transfer is defined as the passage of DNA to objects and people.
Secondary DNA transfer is an extension of this process, where DNA is transferred to an object or person through an intermediary.
This kind of transfer can lead to individuals being falsely linked to a crime scene and can also reduce the likelihood of prosecuting the real criminal due to the introduction of foreign DNA to a forensic sample.
Effect on convictions
High sensitivity DNA kits have only been made available over the last decade. Such kits are now being used to reinvestigate unsolved cases in which minute DNA traces were discovered. Secondary DNA transfer has also been successfully used to overturn wrongful convictions. After a murder in California, USA, a man was charged with murder and spent months in prison before his alibi proved he was innocent. His DNA had been transferred to the crime scene via first responders. Many professionals agree that increased knowledge of secondary DNA transfer will be incredibly important in future cases.
Since the early 2000's, technological advances have improved and yielded more data regarding DNA transfer. Increased advances mean that less DNA is needed to generate full profiles, which can implicate secondary DNA transfer present in minute amounts. There is some evidence that DNA spread does not stop at secondary transfer, with some studies finding tertiary and quaternary DNA transfer.
The most recent DNA testing kits are sensible to secondary transfer. One study indicated that 85% of tests had some degree of secondary DNA transfer. The same study found that in one-fifth of those cases, the DNA by secondary transfer was identified as the only DNA present or as the main contributor of the DNA present.
How often does it happen?
What about people who are falsely accused of a crime?
Secondary DNA transfer could falsely place someone at the scene of a crime. In the above study, DNA typing results indicated that secondary DNA transfer was detected in 85% of the samples.
As for a malicious ‘fit-up’? It may also be possible that a perpetrator of a crime could bring traces of another individual into a crime scene and deposit these traces via secondary DNA transfer.
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