Christina A. Howden, Sandra Day O’Connor College of Law




Somewhere in the basement of the Maricopa County Clerk’s Office, law students are poring over hundreds of tiny pages of criminal court records through the lens of a microfilm reader. Maricopa County digitized records in 2002, but microfilm is still the name of the game if you want to dig back further than 1990.[1]


But, why would anyone would care about cases from over thirty years ago? It turns out that hair microscopy—a forensic process of comparing different hair samples under a microscope to connect people to a crime—is not as accurate as once thought,[2]and cases where hair analysis was used to make an identification are currently getting a second look in Arizona, and other select states and jurisdictions across the country.[3]




Hair microscopy is not new. The first recorded use of the forensic discipline dates back to 1861 in Germany; the first published American opinion was in Wisconsin in 1882.[4]Law enforcement still uses hair microscopy today to test trace evidence from hair left at crime scenes.[5]Lab analysts look through a microscope to compare hair samples from known parties to hair evidence found at the scene to identify similar characteristics (e.g. form, density, color, diameter, etc.). While hair microscopy does not purport to individualize any one person explicitly, an analyst would determine, for instance, if a comparison “includes,” “excludes,” or “matches” related persons.[6]


In theory, the process seems logical and certainly useful to prosecutors. However, lab analysts simply haven’t seen eye to eye about important questions like what a “match” means, which examination approach and classifications to use, how many characteristics must be present, how big of a reference sample is needed, how many other suspects should be compared, or even simple reporting terminology.[7]Further, by the time the forensic findings are conveyed in courtrooms and plea deal negotiations across the country (we’re talking in the thousands), the findings were often overstated (i.e. going beyond the bounds of science) or at least misleading.[8]No big deal, unless your guilt, innocence, or even life, depends on it.[9]


The industry was not without standards, however. In fact, Federal Bureau of Investigation (FBI) Agent John Hicks literally wrote the book on it in 1977.[10]Based on the scientific knowledge at the time,[11]the FBI Lab tested thousands of hair analysis cases nationwide and trained hundreds of state forensic examiners in yearly two-week trainings.[12]




Problems started in 1992, when a whistleblower from within the FBI Lab sparked an investigation into possible misconduct.[13]Adding fuel to the fire was the concurrent explosion of forensic DNA science in criminal law,[14]coupled with negative media attention.[15]In 1997, an Office of Inspector General report was issued and an investigative task force combed through thousands of FBI hair cases.[16]Of the more than 21,700 FBI hair cases identified, 15,000 cases made the cut and were reviewed by 2014. Some 2,100 of those 15,000 had some hair association found that potentially lead to trial testimony or plea bargain negotiations.[17]The outcome? A document was issued outlining new scientific standards,[18]the FBI agreed to review every hair case having positive association with a fine-toothed comb (so long as basic requirements were met),[19]and the United States Department of Justice (DOJ) agreed to waive federal procedural bars in the pursuit of justice so issues in these cases could be heard on their merits.[20]The FBI also issued a mandate that, while still allowing the practice of hair microscopy to continue, required that it be accompanied by DNA testing.[21]


Unfortunately, there were more bad hair days ahead for lab analysts. In 2009, legal and scientific communities teamed up and released a ground-breaking National Academy of Sciences Report which, among other things, took a closer look at the reliability of hair microscopy and noted a lack of uniform standards, high error rates, and “limited probative value.”[22]Then, exonerations began. Three men in a three-year period (2009 -2012)—Joseph Sledge, Santae Tribble, and Kirk Odom—were released from custody in the D.C. area after findings that faulty hair analysis lead to the convictions.[23]As of 2018, 75 of 362 Innocence Project DNA exonerations nationwide were derivative of inaccurate hair evidence.[24]In 2015, the FBI issued a press release proclaiming that its “microscopic hair analysis contained errors in at least 90 percent of cases in ongoing review.”[25]In short, it was time to trim some split ends and sweep up in the criminal justice system.




Today, the FBI review is still ongoing.[26]The DOJ, FBI, Innocence Project, and National Association of Criminal Defense Lawyers (NACDL) are probing lab reports to identify plea cases and tracking down trial transcripts to identify pre-1980 hair cases that occurred before the wave of document digitization began.[27]The FBI Lab is also being audited to figure out how this could have gone on so long in light of evolving science and technology.[28]


But, it isn’t time to let our hair down yet. Problems at the FBI mean problems at home, and the Department of Justice is encouraging states to review their own cases and the credibility of examiners trained by the FBI.[29]In Arizona, this means that over 500 cases need to be reviewed to determine which of these cases involved hair, and therefore require reexamination.[30]


Arizona has heeded the call for review by former FBI Director James Comey.[31]The Arizona review is equipped with a two-year, approximately $500,000 National Institute of Justice grant and man-power from an impressive collaborative task force, including the Attorney General’s Office, Arizona Justice Project, Arizona State University’s Sandra Day O’Connor College of Law, and the Department of Public Safety.[32]The task force, unique in its collaboration from both sides of the “v,” is currently identifying and untangling Arizona criminal cases where (1) hair analysis lead to a conviction, (2) DNA analysis could be performed on hair evidence to prove innocence, or (3) overstated testimony of lab analysts and attorneys who claim to have found a “match” may exist.[33]The grant runs from January 2018 through December 2019.


The Arizona Justice Project, an influential non-profit founded in 1998, and ASU’s Post-Conviction Clinic, composed of dedicated attorneys supervising a team of law students, are closely aligned in their goal of seeking justice for innocent and wrongly-convicted prisoners in Arizona and are working together on the project. Remember that part in the beginning about law students scrutinizing microfilm in the basement of the clerk’s office? This is where that comes in. The research, however, isn’t only happening in Phoenix—cases from all around the state are being tracked down in their respective counties. The University of Arizona’s James E. Rogers College of Law is even reviewing Tucson hair analysis cases under a separate grant.[34]The goal is to have no stone unturned in the ongoing effort to ensure justice for all.




Hair microscopy is not an exact science.[35]Alone, it cannot individually identify a person or say definitively that two hairs “match.”[36]It can exclude a suspect from a hair sample or find association of a person from a pool of possible sources.[37]However, to have more meaningful findings, hair analysis should be paired with DNA testing[38]—for example, mitochondrial DNA (mtDNA) testing in the absence of root or cellular material or Standard Tandem Repeat (STR) testing in the presence of cellular material.[39]And, importantly, hair analysis testimony needs to be portrayed in trials and plea deals fairly and with limiting language, explaining the constraints of the science.[40]After all, people’s lives and futures are at stake.

[1]Michael K. Jeanes, Clerk’s Office Nationally Recognized for Records Project, Maricopa Lawyer (July2017), [].

[2]Paul C. Giannelli, Microscopic Hair Comparisons: A Cautionary Tale, 46 Crim. L. Bull. 3, art. 7 (Summer 2010).

[3]See Spencer S. Hsu, U.S. Reviewing 27 Death Penalty Convictions for FBI Forensic Testimony Errors,Washington Post (July 17, 2013), []; Seth Augenstein, Hair Analysis Review: Dozen States Looking at Criminal Cases, Forensic Magazine(Jan. 6, 2017), [].

[4]Giannelli, supranote 2;Knoll v. State, 12 N.W. 369 (Wis. 1882).

[5]See FBI/DOJ Microscopic Hair Comparison Analysis Review, U.S. Dep’t. of Just., Fed. Bureau of Investigation (Sept. 24, 2018), [].

[6]Giannelli, supranote 2.

[7]See generally James Robertson, Forensic and Microscopic Examination of Human Hair, in Forensic Science Series: Forensic Examination of Hair79, 79-154 (James Robertson ed., 1999).

[8]Wade V. Davies, Attempting to Remedy the Erroneous Use of Microscopic Hair Comparison in Tennessee, 51 Tenn. B.J. 30 (July 2015).

[9]SeeHsu, supra note 3.

[10]John W. Hicks, U.S. Dep’t. of Just., Fed. Bureau of Investigation, Microscopy of Hairs: A Practical Guide and Manual (1977).

[11]Nat’l District Attorneys Association, FBI Responds to Questions Raised About Hair Comparison Analysis, 32Prosecutor 27 (Dec. 1998).

[12]FBI Testimony on Microscopic Hair Analysis Contained Errors in at Least 90 Percent of Cases in Ongoing Review, U.S. Dep’t. of Just., Fed. Bureau of Investigation (Apr. 20, 2015), []; Spencer S. Hsu, FBI Lab’s Woes Cast a Growing Shadow, Washington Post (Dec. 23, 2012), [].

[13]Former FBI Whistleblower Fred Whitehurst Weighs in on Hair Analysis Allegations, Innocence Project (Apr. 28, 2015), [].

[14]Mark Hansen, A Comeback for Hair Evidence, 84 A.B.A. J. 66, 66-67 (May 1998).

[15]See Spencer S. Hsu, Convicted Defendants Left Uniformed of Forensic Flaws Found by Justice Department, Washington Post (Apr. 16, 2012), []; Ed Pilkington, Thirty Years in Jail for a Single Hair: the FBI’s ‘Mass Disaster’ of False Conviction, The Guardian (Apr. 21, 2015), [].

[16]U.S. Department of Justice, Federal Bureau of Investigation,supranote 12.

[17]SeeHsu, supra note 3.

[18]Eric Lichtblau, Justice Dept. to Tighten Rules on Testimony by Scientists, N.Y. Times(June 3, 2016), []; Forensic Science, U.S. Dep’t. of Just. (Sept. 25, 2018), []; Department of Justice Uniform Language for Testimony and Reports for the Forensic Hair Discipline, U.S. Dep’t. of Just. (July 26, 2018), [].

[19]U.S. Department of Justice, Federal Bureau of Investigation,supranote 5.

[20]Innocence Project and NACDL Announce Historic Partnership with the FBI and Department of Justice on Microscopic Hair Analysis Cases: Government Agrees to Notify Defendants of Error, Waive Procedural Arguments and Offer Free DNA Testing, Innocence Project(July 18, 2013), [].

[21]See Department of Justice and FBI Joint Statement on Microscopic Hair Analysis, U.S. Dep’t. of Just., Fed. Bureau of Investigation (Apr. 19, 2015), [].

[22]Nat’l Research Council, Nat’l Academy of Sciences, Strengthening Forensic Science in the United States: A Path Forward161 (2009).

[23]Microscopic Hair Comparison Review Project, Nat’l Association of Criminal Defense Lawyers (Sept. 24, 2018), [].

[24]Featured Cases: Hair Analysis, Exonerated by DNA, Innocence Project (Sept. 24, 2018),,exonerated-by-dna []; Featured Cases: Exonerated by DNA, Innocence Project (Sept. 24, 2018), []; Exonerate the Innocent, Innocence Project (Sept. 24, 2018), [].

[25]U.S. Department of Justice, Federal Bureau of Investigation,supranote 12.

[26]U.S. Department of Justice, Federal Bureau of Investigation,supranote 5.


[28]U.S. Department of Justice, Federal Bureau of Investigation,supranote 12.

[29]James B. Comey, Letter to Additional Governors on State Reviews, U.S. Dep’t. of Just., Fed. Bureau of Investigation (Jun. 10, 2016), [].

[30]State-wide Hair Microscopy Review, Arizona Justice Project (Sept. 24, 2018), [].

[31]Comey, supra note 29.

[32]Arizona Justice Project, supranote 30.


[34]Wrongful Conviction Review Program, Arizona Case Expansion Program,Office of Justice Programs, U.S. Dep’t of Justice, Bureau of Justice Assistance (2016), []; Funding: Grant Awards: FY 2016, Office of Justice Programs, U.S. Dep’t of Justice, Bureau of Justice Assistance, [].

[35]National Research Council, National Academy of Sciences, supranote 22; Jonathan Jones, Forensic Tools: What’s Reliable and What’s Not-So-Scientific, Frontline (Apr. 17, 2012), [].

[36]National Research Council, National Academy of Sciences, supranote 22.

[37]Cary T. Oien,Forensic Hair Comparison: Background Information for Interpretation, Forensic Science Communications, Fed. Bureau of Investigation, Laboratory Division(Apr. 2009), [].

[38]U.S. Department of Justice, Federal Bureau of Investigation,supranote 5.

[39]Nat’l Institute of Justice, DNA Evidence: Basics of Analyzing, (Aug. 9, 2012), [].

[40]Comey, supra note 29.