AuthorCole, Simon A.
PositionMedical condition overview

    In 1998, Charles Johnson, Troshawn McCoy, LaShawn Ezell, and Larod Styles were convicted of the murder of the two owners of a car lot in Chicago. (1) Twenty-three fingerprints and four palm marks were recovered from cars that the perpetrators stole or had encountered on the day of the murder. (2) The marks were compared to the victims and suspects and searched in the local Automated Fingerprint Identification System ("AFIS"). (3) Neither the suspects nor the victims were identified as the sources of any of these marks. (4) No source was identified for twenty-six of the marks. (5) Latent print examiners reported a source for only one mark: a man who had traded in a car at the lot on the day of the crime. (6) This man was eliminated as a suspect. (7) Some of the marks were reported to be of no value for comparison. (8) Others were reported to be of value but not suitable for AFIS searching, and the AFIS lacked the capability to search palm marks at that time. (9) At Johnson and Styles's trial, the prosecutor argued that Johnson might be the source of a mark that had been deemed insufficient for comparison. (10)

    Eleven years later, in 2009 on Johnson's motion, the court ordered the marks analyzed and searched in the Illinois State AFIS. (11) As a result of this search, latent print examiners identified five different men, one being the victim's, as the sources of ten of the marks. (12) Perhaps the most incriminating mark was found on the adhesive side of a window sticker that had been removed from a car that had been stolen from the lot at the time of the murder. (13) Latent print examiners reported that a man named Davion Allen was the source of this mark. (14) The fact that the mark was on the adhesive side of the sticker made it less plausible to claim that the mark had been left during an innocent visit to the lot, rather than after the stealing of the car, which was believed to have followed the murder. (15) Latent print examiners also identified Allen as the source of marks from the examined cars at the lot. (16) Moreover, Allen's home was a short walk from the site where the stolen car had been abandoned. (17) Finding "Mlle fact that the new fingerprint and palm print evidence conclusively matched other people, and now excludes defendant as a match, is significant [,]" (18) the Illinois Appellate Court ruled that Johnson had "made a substantial showing of an actual innocence claim... that... would probably change the result on retrial." (19) Johnson and Styles's convictions were reversed in 2013. (20) Johnson, McCoy, Ezell, and Styles, the "Marquette Park Four," were finally exonerated in 2017. (21)

    The Marquette Park Four's exonerations are an example of a case in which fingerprint evidence played a role in both the wrongful conviction and the exoneration. It did not, however, play the role that is perhaps most often discussed with regard to wrongful conviction and fingerprint evidence--in which an erroneous fingerprint individualization contributes to a wrongful conviction. (22) The classic such case is that of Stephan Cowans, the only case in which a conviction obtained in part through a fingerprint inference of common source was overturned through post-conviction DNA testing. (23)

    The emphasis on erroneous individualizations in the wrongful convictions literature was perhaps a result of the fact that at the time that research into fingerprint evidence and innocence began in the early 1990s the possibility of erroneous identifications was still controversial. (24) The fingerprint profession was at that time claiming--and the courts were accepting--that erroneous identification could not occur and that the error rate of latent print identification was "zero." (25) In this context, it is not surprising that a great deal of energy went into debunking these claims of infallibility. Today, however, even the fingerprint profession itself disavows infallibility claims, and at least one judge has issued a public mea culpa of behalf of the bench for taking them seriously. (26)

    The Marquette Park Four case illustrates that an erroneous individualization is only one of many ways in which latent print error can be implicated in wrongful convictions. In this article, we seek to move beyond erroneous individualizations to discuss more of the various fact patterns through which fingerprint evidence can play a role in wrongful convictions. In Part II, we discuss the methods and materials we used for conducting this study. In Part III, we summarize the nature of latent print analysis and the types of "reports" (or conclusions) this analysis can yield. In Part IV, we introduce a framework for categorizing different types of fingerprint error. In Part V, we discuss each error type. In Part VI, we show that the occurrence of these error types is unsurprising and is, to some extent, an expected product of the way that latent print analysis is structured. In Part VII, we conclude by discussing what we see as the most important criminal justice system reforms for reducing miscarriages of justice contributed to by these "other" fingerprint error types: access to evidence. Most extensively, we discuss the need for AFIS access for defendants both pre- and post-conviction. It should be clear from our capsule description of the Marquette Park Four case that a key turning point in the case was the fact that when Johnson moved that the latent marks be searched in the state AFIS database, the court ordered that this be done. While this may seem an eminently sensible and low-cost decision, in fact, the Marquette Park Four were extremely fortunate to live in one of only five states in the United States with a statutory provision allowing for post-conviction AFIS searching. Without that provision, as we will discuss below, the Marquette Park Four might still be in prison today. We conclude by asking why this should be the case.


    For this study, we conducted an unsystematic survey of known innocence cases in which fingerprint evidence was involved. We obtained our case examples from five sources: (1) the data set of post-conviction DNA exonerations maintained by the Innocence Project; (27) (2) the National Registry of Exonerations, the most comprehensive source of information on U.S. exonerations; (28) (3) a compilation of latent print error cases prepared and maintained by Dr. Erin Morris, a Behavioral Sciences Research Analyst at the Los Angeles County Public Defender; (29) (4) Michele Triplett's Fingerprint Terms, which contains a listing of a number of error instances; (30) and (5) cases of which we had become aware through research and communication with other scholars, lawyers, journalists, and activists, one of us as a post-conviction attorney and innocence advocate and one of us as a researcher on the validity of fingerprint identification. We make no claim that these cases amount to any sort of representative or comprehensive sample of cases. We are also confident that we have missed many cases due to our opportunistic method of data collection. Our discussion of cases is illustrative only.


    Friction ridge (or "latent print" or "fingerprint") analysis concerns the comparison of impressions of friction ridge skin--the corrugated skin on the fingers, palms, and soles--in order to make inferences about whether such impressions may have derived from a common source area of friction ridge skin. (31) For purposes of criminal investigations, such comparisons typically involve the comparison of an accidentally deposited impression, which we shall call a "mark," with a deliberate impression, which we shall call a "print." (32)

    Inferences of source of the mark are effected by comparing the "friction ridge details" of the mark with those of the print. (33) Features that are "in agreement"--that is, in the same relative spatial location within some subjectively defined degree of "tolerance"--support an inference of common source. (34) Features that are not in agreement support an inference of different sources. (35)

    To what extent friction ridge features support inferences of common source--and what inference can be made from various findings of agreement of various configurations of features--has long been a vexing question. While some research on this question has recently been published, (36) the current practice in the discipline is to have the latent print analyst intuit the value--that is, the relative rarity within the relevant population of friction ridge skin --of the friction ridge features observed. (37) While we, and many others, continue to find this practice problematic, (38) that is not our topic here.

    1. Fingerprint Reports

    At least four categories of "reports" (39) of friction ridge analyses are possible: (1) individualization; (2) exclusion; (3) inconclusive; (4) no value. (40) However, actual reporting practices have varied across both agency and time. (41) For instance, many agencies historically reported only identified or not identified, thus compressing the latter three categories into one. (42) Most attention has been focused on the individualization report. (43) The purpose of this Article, however, is to draw attention to the probative value of the other report types. Therefore, we will briefly discuss each.

    1. Determinations of Value

      Recent efforts have greatly enhanced the latent print discipline's description of the process of latent print analysis. (44) Of particular importance for our purposes is the fact that latent print analysis is supposed to begin with a determination of value. (45) In other words, the analyst is supposed to decide whether the mark contains enough information to make an inference. If not, there is (perhaps) no reason to continue further with the analysis. However, even this determination has been muddied by recent discussions which make clear that latent print units are not consistent in how they use the term...

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