- Microscopic hair analysis and comparison has been admissible in court for many years – however, the 2011 Daubert amendments to Rule 702 and recent studies questioning the overall accuracy of the science may limit the scope of what is admissible in the future.
- The witness may testify that two hairs are “consistent” and therefore could have come from the same person, but the witness cannot conclusively say that the hair did come from one specific individual.
- But the witness can conclusively say that a specific individual is not a match, if the hairs are inconsistent.
- Microscopic analysis may also reveal whether a hair was removed by force or rubbing, as opposed to being cut or simply falling out on its own.
Reliability and Admissibility
Hair analysis is conducted by looking at the microscopic characteristics of a human hair sample (e.g., hair recovered off the victim’s clothes) and comparing them to the characteristics of the defendant’s hair. This analysis is less precise than a DNA or fingerprint comparison, so the analyst will not be able to testify that any two hairs are a “match,” but the analyst should be able to say that the hairs are (or are not) “microscopically consistent.” A proper foundation must be laid before introducing any testimony from the expert regarding the “statistical probability” that the microscopic characteristics of defendant’s hair would match another person’s hair. See State v. Suddreth, 105 N.C. App. 122 (1991) (witness permitted to testify that hair characteristics would only match one person out of a thousand); but see State v. Bridges, 107 N.C. App. 668 (1992), aff’d per curiam, 333 N.C. 572 (1993) (insufficient foundation offered to permit testimony about statistical probability).
Historically, North Carolina courts have admitted hair analysis evidence to prove identity, as long as it is relevant – that is, hair analysis evidence is admissible as long as it “reasonably tends to establish the probability or the improbability of a fact in issue.” State v. Green, 305 N.C. 463 (1982) (expert on hair identification properly permitted to testify that a pubic hair found on the body of a rape victim—which did not originate from her—had the same microscopic characteristics as pubic hair taken from defendant and therefore could have come from defendant); State v. Vestal, 278 N.C. 561 (1971) (no error to allow an expert in the field of analyzing and comparing hair to testify regarding the similarity of hairs found in a warehouse and trunk of the defendant's automobile with hairs taken from the head of the victim’s body) State v. Barber, 278 N.C. 268 (1971) (trial court did not err by allowing expert to testify that hairs from scene “and hair taken from the defendant were microscopically identical in all identifying characteristics. He concluded that these hairs from the bed could have come from the defendant.” The testimony established that the perpetrator was of the same race as the defendant, and was therefore another “link in the chain” proving that the defendant was in fact the perpetrator); State v. McCord, 140 N.C. App. 634 (2000) (the trial court did not abuse its discretion by admitting expert testimony that a pubic hair taken from the victim was microscopically consistent with a known sample of defendant’s pubic hair; “because the comparison of hair samples has been accepted as reliable scientific methodology in this State, the trial court properly allowed [the analyst] to testify regarding the results of his testing”); State v. Suddreth, 105 N.C. App. 122 (1992) (“Our courts have liberally permitted the introduction of expert testimony as to hair analysis when relevant to aid in establishing the identity of the perpetrator.”).
More recently, in light of evidence of errors with this type of analysis, the scientific community and some courts have expressed doubts about the accuracy and reliability of this process. See, e.g., President’s Council of Advisors on Science and Technology (“PCAST”) 2016 report, Section 5.7, pages 118-122 (citing an FBI study in which 11% of purported hair “matches” were found to be incorrect based on subsequent DNA testing, and finding that materials provided by the Department of Justice “do not provide a scientific basis for concluding that microscopic hair examination is a valid and reliable process”).
There are not yet any North Carolina appellate cases which have re-examined the admissibility of hair analysis and comparison in light of the 2011 Daubert amendments to Rule 702. Other courts that have conducted a Daubert-style reliability assessment of hair analysis are divided in their determinations of whether the tests should be admissible or not; some courts have continued to allow the evidence, while others have excluded or limited it. See, e.g., State v. Fukusaku, 946 P.2d 32 (Haw. 1997) (“Because the scientific principles and procedures underlying hair and fiber evidence are well-established and of proven reliability, the evidence in the present case can be treated as ‘technical knowledge.’ Thus, an independent reliability determination was unnecessary.”); McGrew v. State, 682 N.E.2d 1289 (Ind. 1997) (concluding that hair comparison is more a matter of observation by persons with specialized knowledge than a matter of scientific principles); Butler v. State, 108 S.W.3d 18 (Mo. Ct. App. W.D. 2003) (without the benefit of population frequency data, expert witness overreached in opining to “a reasonable degree of certainty that the unidentified hairs were in fact from” the defendant).
What about getting DNA instead?
Due to the current uncertainty about the admissibility or hair analysis at trial or on appeal, the prosecutor should consult with the analyst and ask whether it would be possible to use the hair sample to conduct a DNA comparison instead, which will likely yield much more specific results. See State v. Underwood, 134 N.C. App. 533 (1999) (allowing expert testimony regarding mtDNA analysis of hair sample). For more information, see the related entry on Expert Testimony - DNA Evidence.
Specific Identification vs. Specific Exclusion
As noted above, hairs found at a crime scene may have characteristics of race and hair color that are microscopically consistent with a hair sample taken from the defendant, and therefore, the jury may conclude that the hairs found at the crime scene could have originated from defendant. See State v. Pratt, 306 N.C. 673 (1982) (SBI analyst testified only that “pubic hair found on [the victim and] . . . pubic hair samples obtained from defendant . . . [were] ‘microscopically consistent’” but did not conclusively identify the perpetrator of the crime). The jury decides the weight and credibility to give to such evidence. See State v. Payne, 328 N.C. 377 (1991) (agent’s testimony that “the hair had some characteristics, albeit limited, consistent with defendant's head hair tends to make defendant's contact with the victim more probable. That the characteristics identified in the hair could be consistent with hair from persons other than defendant or the victim goes to the weight, not the admissibility, of this evidence.”); State v. Green, 305 N.C. 463 (1982); State v. Hannah, 312 N.C. 286 (1984); State v. Suddreth, 105 N.C. App. 122 (1992).
However, unlike DNA or fingerprint evidence, hair analysis evidence is not accepted as reliable for the purpose of positively identifying a specific person. See State v. Faircloth, 99 N.C. App. 685 (1990) (“[u]nlike fingerprints… comparative microscopy of hair is not acceptable as reliable evidence to positively identify a person. Rather, it serves to exclude classes of individuals from consideration and is conclusive, if at all, only to negative the identity.”). In other words, the evidence can be used to conclusively disprove identity by excluding certain classes of individuals from consideration (e.g., a long and straight blonde hair found at crime scene could not possibly have come from a defendant with short and curly red hair). See State v. Stallings, 77 N.C. App. 189 (1985); State v. Bridges, 107 N.C. App. 668 (1992); State v. Head, 79 N.C. App. 1 (1986).
Procedures for Collecting Defendant’s Hair Sample
Warrantless Seizure Incident to Arrest/Custody:
A hair sample may be collected when the defendant is placed under arrest or being held in custody. See State v. Steen, 352 N.C. 227 (2000) (“this Court has approved the taking of samples of a defendant's hair and saliva as long as one day following a defendant's arrest and upon the basis of the defendant's being in police custody, rather than on the basis of the taking being incident to arrest. […] Accordingly, we hold the trial court did not err in concluding that neither a court order nor a search warrant was necessary for the police to take hair and saliva samples from defendant in the instant case.”) (internal citation omitted); State v. Thomas, 329 N.C. 423 (1991) (“The trial court committed no error in admitting evidence of defendant's fingernails, pubic hair, teeth, saliva, and lips, because that evidence was properly obtained while defendant was in police custody”); State v. Sharpe, 284 N.C. 157 (1973) (plucking of hair samples from defendant's head and arm for microscopic examination, without a warrant, was reasonable since such hairs were in plain view and the samples were not taken in any forcible or unreasonable manner).
Nontestimonial Identification Order, or Search Warrant
A nontestimonial identification order (or search warrant) may be used to obtain a sample for comparison if the defendant is not in custody. See G.S. 15A-271 et seq., and the related Pretrial entry on Nontestimonial Orders.
Finally, a defendant can always consent to providing a hair sample. See State v. Reynolds, 298 N.C. 380 (1979) (“the record discloses the defendant clearly consented to the taking of the hair sample after the officers explained that he was not required to do so. Hence, this assignment of error is overruled”).
Analysis to Show That Force Was Used
Finally, if force is an element of the crime being prosecuted, a hair analysis expert may be permitted to testify about whether it appears that force was used to remove the victim’s hairs. See State v. McNicholas, 322 N.C. 548 (1988) (presence of tissue attached to the root of the hair indicated that the hair was removed by some type of force, rather than simply falling out at the end of its natural lifecycle).