How new DNA technologies are changing criminal investigations

Using DNA evidence, Richland County investigators were able to solve a grisly murder from 30 years ago


By W. Thomas Smith Jr., P1 Contributor

In early March 2017, the Richland County Sheriff’s Department’s (RCSD) Cold Case Unit was able to solve a grisly murder case that had baffled investigators in central South Carolina for decades.

Thirty years earlier, 34-year-old Patricia Ann Green was shot in the face at pointblank range and her body left in a roadside ditch near the heavily trafficked main gate of McEntire Joint National Guard Base in Eastover, S.C. The motive for Green’s killing was simple: She was in the wrong place at the wrong time and had encountered the wrong man, Phillip Johnson, today a 54-year-old inmate serving life-terms for four other murders, who in 1987 was on a killing spree.

In this Feb. 17, 2012, file photo, senior criminalist Michelle Halsing works on mitochondrial DNA testing at the State of California Department of Justice Jan Bashinski DNA Laboratory in Richmond, Calif. (AP Photo/Jeff Chiu, File)
In this Feb. 17, 2012, file photo, senior criminalist Michelle Halsing works on mitochondrial DNA testing at the State of California Department of Justice Jan Bashinski DNA Laboratory in Richmond, Calif. (AP Photo/Jeff Chiu, File)

The Green murder is one of eleven (out of 81 unsolved cases since 1960) that have been solved since 2000 by the department’s Cold Case Unit; a five-person team of retired law-enforcement investigators formed in 1997, the first year Richland County Sheriff Leon Lott took office and a decade after Green was killed.

Like many others, the key to solving this crime was the introduction of DNA evidence, which was discovered on an article of her clothing.

What is DNA?

DNA or deoxyribonucleic acid is essentially a molecule with genetic instructions that program living organisms in the development, growth and function of those organisms. DNA is unique with every person.

“We gather DNA material from blood, semen, saliva, urine, feces, hair, teeth, bone and tissue, as well as cells from dead skin,” said Lott. “We leave traces of our DNA everywhere we go, and though one person’s DNA is unique, DNA can be matched to family members.”

Family DNA is increasing the successes in solving cold cases.

According to an article by NBC News: “Police are harnessing consumer DNA sites to solve old murders, which could spur a massive clearing of unsolved crimes.” The consumer sites are primarily online ancestry and public genealogical databases where those who are researching their family backgrounds submit samples of DNA to make family connections. Pairing ancestry interest with sophisticated DNA technology “could revolutionize law enforcement,” say the experts interviewed by NBC.

What’s next?

“The next step in DNA technology as it relates to criminal investigations is phenotypic marking,” said Dr. Gray Amick, director of RCSD’s forensic laboratory.

According to Amick, a person’s phenotype is essentially his or her genetic type which expresses how that person will look physically: Hair color, skin color, eye color, even possible height and weight and geographic ancestry to general propensities toward physical maladies and diseases.

“In regard to investigations, we will be able to develop a forensic artist’s sketch of what a person looks like based on DNA,” said Amick. “This so-called next generation sequencing has application not only in paternity testing but in forensic investigations. That’s where I believe DNA technology is going in terms of solving criminal cases.”

Before DNA technology

When Patricia Ann Green was murdered in 1987, biometric forensics were primarily limited to fingerprints, which is still a viable means of collecting evidence, but not helpful in that particular case because there were no fingerprints left by the killer on any of the collected evidence.

The following year, 1988, now-convicted murderer Colin Pitchfork of Leicestershire, England became the first-ever person to be arrested, tried, convicted and sentenced based on DNA evidence with technology developed at the University of Leicester and researchers with the UK’s Forensic Science Service.

“When DNA technology for criminal investigations was introduced many years ago, cold case units began vetting cold cases to see what evidence was in the evidence room that might have DNA evidence attached to it,” said Deputy Chief Stan Smith, commander of RCSD’s Criminal Investigations Division. “Yet it remains a challenge, because 40 or 50 years ago, no one would have anticipated that a bloody blouse or fingernail scrapings would one day have any evidentiary value because no one really knew anything about DNA.”

DNA technology has changed everything

DNA was widely used immediately after 9/11 to help identify many of the 2,600-plus victims of the terrorist attacks on the World Trade Center in New York. In the wake of the attacks, mouth swabs were taken from persons who had missing family members believed to have perished when the towers collapsed.

DNA biometrics have since been utilized in numerous other applications from crime-fighting and counterterrorism to medical research, and the aforementioned genealogical research and paternity testing.

As successful as DNA technology has been in solving cold cases, even in preventing acts of terrorism, Sheriff Lott also believes the applications are still in their infancy.

“Even with the new genetic typing and phenotypic marking that we will see in its investigative applications within the next 10 years, we have to ask where the technology will take us beyond that,” said Lott.

Rapid DNA testing

DNA testing in a forensics laboratory like RCSD’s is one thing, but “rapid DNA” testing machines – devices not much bigger than desktop laser printers – are now being used that can be easily operated by a non-tech person, and they can produce accurate science-based match-results in as little as 90 minutes. Moreover, the size of the Rapid DNA machine is such that it can be carried into the field.

“Rapid DNA is a highly sophisticated technology combined with a relatively new user-friendly application of that technology virtually unheard of until a few short years ago,” said Lott. “And with greater intelligence-sharing and the ever-expanding DNA database being developed worldwide, Rapid DNA technology can not only enable us to track criminals and solve crimes faster and more easily, but it can serve as a means by which terrorists and terrorism can be stopped dead in its tracks before an attack is ever launched in this country.”

Not all American law enforcement agencies have Rapid DNA technology in place. RCSD has integrated it into its forensics lab, and the department is currently the only law-enforcement agency in South Carolina with the Rapid DNA technology in-house.

“Rapid DNA simply enhances our biometric forensics capability,” said Lott. “It is absolutely proving its worth in solving mysterious crimes relegated to the RCSD Cold Case Unit, and it is only going to improve, expand to other agencies, ultimately become more portable, and in-the-long-run save lives.”

The question remains: As DNA science continues along its now near-exponential track of increasing sophistication, will DNA technologies to include genetic sequencing and simple-to-use rapid-results-producing equipment replace the fingerprint technology agencies have heavily relied on for decades?

“The short answer for the near and not-so-near future is no,” said Lott. “Fingerprinting is still reliable, accurate and virtually without cost.”

Beyond that, the Sheriff explains, law enforcement agencies, both nationally and worldwide, still maintain a huge fingerprint database from which to draw on.

“That database continues to serve us well, and it’s not going anywhere,” said Lott.


About the Author
W. Thomas Smith Jr. is a special deputy with the Richland County Sheriff’s Dept.

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