Please ensure Javascript is enabled for purposes of website accessibility
Home / Opinion Digests / Criminal Practice / Criminal Practice  – Evidence – DNA Expert – Inconclusive Sample – Allele Match – Statutory Rape

Criminal Practice  – Evidence – DNA Expert – Inconclusive Sample – Allele Match – Statutory Rape

Defendant’s anticipated defense to a charge of statutory rape was that the 13-year-old victim’s 21-year-old female friend performed sex acts on the victim, thereby transferring defendant’s DNA to the victim. It was thus prejudicial error for the trial court to allow the state to elicit testimony from its DNA expert—which testimony the expert protested as she gave it—that of six alleles in an inconclusive DNA sample, only three matched the female friend’s DNA.

Defendant is entitled to a new trial.


The testimony of the victim (C.C.), her friend (Justine), and defendant varied significantly as to what happened at the 36-year-old defendant’s apartment, and defendant’s testimony varied significantly from statements he had made to the police.

Internal and external DNA samples taken from C.C. were consistent with defendant’s DNA. However, in C.C.’s external genitalia swab, there was also a minor contributor, and tests of the minor contributor’s DNA were inconclusive.

In a prior trial, defendant had argued that the minor contributor’s sample came from Justine. A jury acquitted defendant of several charges and could not reach a verdict on the statutory rape charge that was the subject of the retrial sub judice.

The state’s DNA expert testified about the sufficient DNA samples. When the prosecutor asked her about allele matches between the minor contributor’s DNA profile and Justine’s, the expert said such testimony would be unscientific. Defendant objected under N.C. R. Evid. 702, and the trial court conducted voir dire of the expert.

The expert insisted that no laboratory in the country would make such comparisons. The prosecutor told the judge about defendant’s defense in his first trial.

The trial court permitted the prosecutor to question the expert about the minor contributor’s profile in front of the jury. The expert testified that three of six alleles matched Justine’s DNA profile and three did not.

The jury found defendant guilty, and defendant appeals.


Although the expert testified to the alleles she “saw,” the alleles she “saw” were numbers on the graphs she had prepared, using her expertise and experience as a forensic scientist. Her testimony moved beyond reporting what she had seen through her senses and turned to assessment and analysis based on her specialized knowledge. Despite the state’s careful framing, she was asked and rendered expert opinion testimony and interpretations subject to the requirements of Rule 702(a).

Under Rule 702(a), expert opinion testimony must be “based upon sufficient facts or data[,] the product of reliable principles and methods,” and the expert witness must “[apply] the principles and methods reliably to the facts of the case.” The expert’s testimony regarding the minor contributor’s alleles was neither based upon sufficient facts or data nor was the product of reliable principles and methods. As an admitted expert witness, she even testified to this absence or omission of reliability herself.

By repeatedly asking the expert to break with the State Crime Lab’s policy and established scientific procedures and testify to the alleles she could see in the minor contributor’s graph, the state asked the expert to give expert opinion testimony based upon admittedly insufficient facts or data in violation of the first prong of Rule 702(a).

The testimony also violated the second prong of Rule 702(a). The expert further disclaimed, repeatedly, that the testimony she was required to give was “not scientifically accurate.” The challenged testimony, describing the alleles of the minor contributor, was neither “based upon sufficient facts or data” nor “the product of reliable principles and methods.” Rule 702(a)(1)-(2). The trial court erred in allowing and admitting this testimony over defendant’s objection.

The expert analyzed five DNA samples, four of which contain mixtures of two contributors and one which contains a mixture of three. Defendant is matched to or consistent with at least one contribution in each of the five samples. C.C. is matched or consistent with at least one contribution in each, except for a tank top defendant gave her to wear. Justine did not match any of the conclusive contributor profiles. Only one sample, the underpants, does not contain an inconclusive contributor; the other four all have an inconclusive contributor in at least one fraction.

A third DNA contributor present in the external genitalia swab raises the possibility that Justine was the means by which defendant’s DNA was transferred to and found on the swabs taken from C.C.’s body. If the state had not insisted on preemptively forcing its expert to state the unscientific and reluctant testimony that allowed the jury to more easily infer Justine could not have been the minor contributor, a reasonable possibility existed a jury would have reached a different result at trial. The prejudice to defendant was not overcome by the state’s other evidence tending to show defendant’s guilt.

New trial.


(Dillon, J.) The testimony at issue did not violation Rule 702, as it was scientifically accurate. The testimony was both irrelevant and unduly prejudicial; however, defendant did not object pursuant to N.C. R. Evid. 402 or 403. Therefore, we review for plain error.

I do not think it is reasonably possible that the jury reached its verdict based on the expert’s testimony concerning certain DNA found on a swab from outside C.C.’s genital area. Defendant’s explanation of how his DNA was found on and inside of C.C. is simply incredible, given that the DNA from the third source was found only on a swab taken from the external area of C.C.’s genitals and that defendant changed his story between the time he spoke with investigators and the time of trial.

State v. Phillips (Lawyers Weekly No. 011-317-19, 37 pp.) (John Tyson, J.) Appealed from Catawba County Superior Court (William Wood, J.) Alexander Peters for the state; Drew Nelson for defendant. N.C. App.

Leave a Reply

Your email address will not be published. Required fields are marked *