by Douglas Ankney

The Supreme Court of South Carolina reversed Billy Phillips’ murder conviction because the State presented improper testimony regarding DNA evidence and provided information to the jury that was simply wrong.

Well-known drug dealer Darius Woods was found shot to death on his couch. His handgun — the murder weapon — was laying on his chest. He was known to carry large amounts of cash, and his pockets were turned inside out, indicating robbery. After his arrest, Phillips filed a pretrial motion seeking to exclude the expert testimony of Lilly Gallman regarding DNA testing she had performed. The trial court held a hearing on the motion but did not take any testimony. The trial court ruled Gallman’s testimony was admissible.

Gallman testified that of the 13 DNA samples submitted for testing only 11 samples contained enough DNA for testing. She testified that the samples were “touch DNA.” (Touch DNA, also known as “trace DNA,” comes from epithelial cells that are deposited after a person touches or handles an object.) Gallman compared the DNA samples prepared from the remaining 11 samples with a sample submitted by Phillips. She testified that he was excluded as a contributor from all but two of the samples.

The sample taken from the murder weapon and the sample taken from the inside of Woods’ pants pocket contained a mixture of DNA from at least three people. Gallman testified that Woods and Phillips “c[ould] not be excluded as contributors” to the mixtures in either sample.

Concerning the sample taken from the gun, Gallman further testified that “the probability of randomly selecting an unrelated individual who could have contributed to this mixture is approximately one in two hundred.” As to the pants pocket, she testified the probability was “one in two.” At one point during the trial, the prosecutor referenced three people handling scissors and asked “if ... you find that there’s at least three, that just means I have left part of my DNA on there. Correct?” Gallman answered: “It means that you left cells, skin cells on that item.” At no point did Gallman inform the jury that the touch DNA samples contained only a fragment of a DNA profile.

The State also presented to the jury the videotape of the pre-arrest police interview of Phillips. He stated he had been to Woods’ home several times the day of the murder, smoking pot and drinking alcohol. He stated he had handled Woods’ gun while imitating law enforcement.

In her closing argument, the prosecutor told the jury: “If you don’t touch it, you are automatically excluded. One hundred percent excluded. Well, we have his DNA on that gun [and] we also know that defendant’s DNA ... is inside [Woods’] pocket. Had he not touched the gun or the pocket, his DNA would not be there.” Phillips was convicted, and he appealed. One argument on appeal was that the trial court erred in admitting Gallman’s testimony because its probative value was outweighed by the danger of unfair prejudice, confusing the issues, and misleading the jury.

The South Carolina Supreme Court observed “[w]hen admitting scientific evidence under Rule 702, the trial judge must find the evidence will assist the trier of fact, the expert witness is qualified, and the underlying science is reliable.” State v. Council, 515 S.E.2d 508 (S.C. 1999).

This is part of the trial court’s “gatekeeping role” regarding the admission of expert testimony. Id. The proponent of scientific evidence has a corresponding responsibility to provide the trial court with the factual and scientific information needed to carry out its gatekeeping duty. Id. The test outlined in Council is materially similar to the federal test in Daubert v. Merrill Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).

If the evidence is admissible, it must then be balanced against “the danger of unfair prejudice, confusion of the issues, or misleading the jury.” SCRE, Rule 403. In most cases, the risk of confusing or misleading a jury with DNA evidence is low because the DNA evidence is usually straightforward and reliable, and its probative force is highly persuasive. Council. Complete DNA profiles have been used to show that the probability was greater than 99.9% that a particular person was the source of the DNA. State v. Ramsey, 550 S.E.2d 294 (S.C. 2001). Because the persuasiveness of DNA evidence is so great upon the minds of jurors, “when DNA evidence is introduced against an accused at trial, the prosecutor’s case can take on an aura of invincibility.” People v. Wright, 37 N.E.3d 1127 (N.Y. 2015).

But in most cases involving only touch DNA, including the instant case, the DNA evidence is not worthy of the same confidence because touch DNA samples usually provide only a fragment of the DNA profile. A complete DNA profile contains all of the alleles (genetic markers) in a sequential pattern or chain unique to each individual. But a fragment contains only a piece of the chain representing a partial pattern that may be found in more than one person’s DNA. (For illustrative purposes only, suppose one person’s alleles were in a pattern identified as A - G - E - B - F and another person’s were identified as C - G - E - B - D. A fragment found to have the pattern G - E - B could belong to either person.) “Touch DNA poses special problems because epithelial cells are ubiquitous on handled materials, because there is an uncertain connection between the DNA profile identified from the epithelial cells and the person who deposited them, and because touch DNA analysis cannot determine when an epithelial cell was deposited.” Hall v. State, 569 S.W.3d 646 (Tex. Crim. App. 2019).

Additionally, the size of the fragment determines an analyst’s ability to determine the probability that a random person other than the suspect was the source of the DNA. In the instant case, Gallman testified that the probability of someone other than Phillips being the contributor to the DNA recovered from Woods’ pocket was one in two. That meant any person from half of the world’s population could have left the DNA. This, in turn, meant the probative value of the evidence in identifying Phillips as the person who had his hands inside Woods’ pocket robbing him was almost zero while the risk of confusing and misleading the jury was great.

This error was compounded by both Gallman’s testimony and the prosecutor’s closing argument. Each misled the jury into believing that the only way a fragment matching Phillips’ DNA could be found on the gun and in the pocket were if Phillips had touched both. But as explained earlier, a DNA fragment is not unique to an individual person. The touch DNA in this case could have been left by a person other than Phillips even though the fragment contained some alleles found in a pattern similar to some of Phillips.’

Additionally, “[t]ouch DNA is ... subject to what is known as secondary transfer. This refers to the possibility that an individual or an object may serve as a conduit between a source and a final destination without any direct encounter.” Bean v. State, 373 P.3d 372 (Wyo. 2016). That is, suppose a person deposits epithelial cells when touching a coffee cup. A second person then handles that cup and the deposited epithelial cells are transferred to the second person’s hands. The second person then handles a pistol and deposits the first person’s epithelial cells onto that pistol. The first person’s DNA would be found on the pistol even though that person never touched the pistol. [Editor’s note: See the cover story of the September 2018 issue of CLN for an in-depth discussion of the dangers of using secondary DNA transfer evidence in criminal cases.]

Finally, the South Carolina Supreme Court concluded that the trial court failed in its gatekeeping responsibility. The trial court neither took any testimony at the pretrial hearing nor conducted any analysis to determine whether the probative value of the DNA evidence was outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury. And the prosecutor failed to provide the trial court with any scientific information to enable it to make that determination. The Supreme Court instructed: “DNA evidence is a complicated scientific subject.... [I]f an objection is made, the trial court must hold a Daubert/Council hearing, the proponent of the evidence must present the factual and scientific basis necessary to satisfy the foundational elements of Rule 702, and the trial court must conduct an on-the-record balancing of probative value against the applicable Rule 403 dangers.”

The Court concluded that by not conducting the Daubert/Council hearing, the trial court left itself without a meaningful opportunity to exercise its discretion; the State failed to establish Gallman’s testimony would assist the trier of fact; and the probative value of the DNA evidence was substantially outweighed by the danger the evidence would confuse the issues and mislead the jury.

Accordingly, the Court reversed the convictions and remanded for a new trial. See: State v. Damme, 944 N.W.2d 98 (Iowa 2020). 

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