Since the introduction of DNA fingerprinting technology or DNA profiling in 1984, the extraction of DNA from human biological fluids (e.g. blood, saliva, semen) has become a daily occurrence in forensic DNA labs worldwide. Over the years, the technology to extract DNA has become even more sophisticated.
What is Touch DNA?
One such technology is called "Touch DNA" or "Contact Trace DNA." Touch DNA refers to the DNA that is recovered from skin (epithelial) cells that is left behind when a person touches or comes into contact with items such as clothes, a weapon, or other objects. A person sheds about 400,000 skin cells per day, but it is the lower skin cells that will provide the best DNA profile. These cells are typically recovered when force is used such as on the victim's clothes or at a crime scene after a struggle has occurred.
These epithelial cells can be lifted with a tape, swabbed with a Q-tip, or even scraped from the clothes of the victim, or objects. Even food can be scraped for skin cells. According to the Bode Technology Lab, as little as 5 to 20 skin cells are all that is required to obtain a Touch DNA sample.
Tim Masters and the Peggy Hettrick Murder
One case that has brought national and international attention was when Touch DNA helped determine the innocence and secure the release of accused killer Tim Masters from a prison in Colorado in 2008.
On February 11, 1987, the semi naked body of 37 year old Peggy Hettrick was found in a field near Fort Collins. She was stabbed in the back with a knife and her body had been sexually mutilated. Police followed the bloody trail from the nearby road to the field where she had been dragged and dumped. The medical examiner noticed that the wounds were "neatly" executed cuts and he remarked that in his 21 years of doing autopsies he had never encountered wounds like these. He even called the wounds "surgical."
At the time, 15 year old Tim Masters lived with his father in a mobile home near where Hettrick's body was found. Masters admitted to the police that he had walked by the body on his way to school but did not notify authorities.
No DNA from the victim was found on Masters and none of Master's DNA was found on the victim. Nonetheless, in 1998, eleven years after the murder and after he was honorably discharged from the Navy, Masters was arrested for the murder of Peggy Hettrick. During the trial, a forensic psychologist testified that Master's "disturbing artwork" had revealed that he had "displaced sexual matricide, stemming from Masters' feelings of abandonment by his dead mother." The psychologist concluded that Master's drawings "fit the profile of a killer because he's alone, he comes from an isolated or deprived background, and he harbored hidden hostility toward authorities as well as violent fantasies." This forensic psychologist never met or interviewed Masters. In 1999, Masters was convicted for the Hettrick's murder and sentenced to life in prison.
In 2003, Masters pursued an appeal on the grounds of ineffective counsel and was appointed new defense counsel, Maria Liu. When Liu studied the huge case file, she found it incredible that Masters was convicted in large part because of his high school artwork.
In 2007, Master's new defense team which included former Fort Collins police detectives who had doubts about Masters conviction, tested the clothes that Peggy Hettrick wore during her murder using the innovative technique - Touch DNA. Master's team enlisted the aid of the Dutch forensic team of Richard and Selma Eikelenboom. Richard is a DNA forensic scientist and Selma is a forensic pathologist. The Eikelenbooms had worked at the Nederlands Forensisch Instituut, and had started their own company, Independent Forensic Services in 2005.
If there were any skin cells left on the clothes of the killer, the Eikelenbooms would find them and create a DNA profile. With the Colorado court's approval, Hettrick's clothes were locked in a suitcase and flown with a veteran of the Colorado state crime lab to The Netherlands. Eikelenboom was able to cut and tape more than 50 points on Hettrick's clothing and retrieve a full genetic profile in the interior lining of her underwear. This male DNA profile was also on the cuffs of the blouse of Hettrick, suggesting the killer may have carried or dragged her by the wrists.
This profile was not that of Tim Masters, but rather that of Hettrick's ex-boyfriend Matt Zoellner. Based on this new evidence, a Colorado Judge threw out Tim Masters' 1999 murder conviction. On January 22, 2008, Masters was free after spending more than nine years behind bars. On February 16, 2010, the Larimer County commissioners approved payment of $4.1 million to Tim Masters to settle claims brought forward in his lawsuit alleging wrongful imprisonment. Zoellner was never arrested for Hettrick's murder. Apparently, Colorado law enforcement believes that there was nothing strange about his skin cells being found on his ex-girlfriend's clothes.
Since the Masters case, the Eikelenbooms, have become recognized as forensic mavericks and leaders in the new field of Touch DNA. Today, their services are in high demand by both prosecutors and defense teams from the U.S. and around the world.
The JonBenét Ramsey Case
In 2008, Bode Technology Lab was able to perform Touch DNA on the clothing worn by six year old JonBenét Ramsey at the time of her murder. A full DNA profile was obtained of a still unidentified male, presumably the killer. In addition to providing a DNA profile, the discovery of a Touch DNA sample on a victim or object can provide law enforcement with important evidence such as how the perpetrator removed clothes from the victim and how long an object was held at a crime scene.
1996 Rape Solved
Using Touch DNA technology, police labs are re-evaluating cold cases. For example, in 2008, the Maryland State Police Lab had a private lab re-examine the clothes of a 12 year old girl who was raped in 1996. The lab retrieved a full DNA profile of the rapist's skin cells - a man who was already incarcerated for another rape he committed in 1996. With the Touch DNA evidence, the 51 year old rapist was ultimately convicted of this second rape.
Touch DNA is proving to be an extremely valuable forensic tool in collecting all evidence left behind by a perpetrator. Today, both older cases and current cases are taking advantage of this innovative technology.