Latent Prints: A Perspective on the State of the Science
Peterson, Peter E., Dreyfus, Cherise B., Gische, Melissa R., Hollars, Mitchell, Roberts, Maria Antonia, Ruth, Robin M., Webster, Heather M., Soltis, Greg L., Forensic Science Communications
For more than 100 years, the science of latent print examination has provided a powerful tool in the investigation of crime. Given its early use, it is not surprising that the latent print discipline developed a period of relatively unquestioned acceptance. However, the recent introduction of newer forensic sciences such as DNA analysis and the widespread attention given to some errors that have occurred within these disciplines have lead to increased scrutiny of all forensic sciences (Budowle et al. 2009). Such scrutiny is healthy and desirable in any scientific endeavor because it generally leads to the advancement of the sciences. The science of latent prints is currently undergoing review both internally and externally in response to such scrutiny and will continue to evolve.
In this article we review the latent print discipline by addressing many of the fundamental topics associated with latent print examination. These topics include:
* The basic premises of persistence and individuality.
* The ACE-V (Analysis, Comparison, Evaluation, and Verification) methodology.
* Standards for the conclusions in latent print examinations.
* Standards for the sufficiency of friction ridge impressions for individualization.
* The role(s) of statistical models in the latent print discipline.
* Errors and error rates in latent print examination.
* Quality assurance and documentation standards in the latent print discipline.
* The training and qualifications of latent print examiners.
* The Scientific Working Group on Friction Ridge Analysis, Study and Technology (SWGFAST).
In the following sections we define each topic, identify issues of concern, clarify issues of confusion, and make recommendations for the advancement of the science. The content of this article should not be construed as a comprehensive review of the entire latent print discipline, nor is it expected that every member of the latent print community will agree with every statement made herein. We wrote this article from our perspective as FBI Laboratory latent print examiners. Other agencies and laboratories may vary in policies and practices.
Persistence and Individuality
The latent print discipline is founded on the premises of the individuality and persistence of friction ridge skin (Wertheim and Maceo 2002). These particular characteristics of friction ridge skin were first observed as early as the 1600s, but they were more substantially established after several studies conducted in the late 1800s by such pioneers as Dr. Henry Faulds and Sir Francis Galton (Ashbaugh 1999). The results of these studies provided the initial support for the tenet that friction ridge skin could be used to individualize. More scientifically rigorous studies of the individuality and persistence of friction ridge skin have been conducted since these early studies, and research is ongoing in both of these areras (Berry et al. 1989; Maltoni et al. 2003).
Today, the premises of the persistence and individuality of friction ridge skin are well supported. The most effective support lies in an understanding of the development of the friction ridge skin during fetal growth. Research has shown that arrangements of friction ridge skin are initiated and subsequently develop through a process of differential growth at the interface between the epidermal and dermal layers of the skin, thereby accounting for their "infinite" variability (i.e., individuality) (Babler 1987, 1991). Research has also shown how the structure of the skin allows continual renewal throughout a person's lifetime of the specific friction ridge arrangements (i.e., persistence) (Cummins 1967; Hale 1952).
Additional studies also support the premises of the persistence and individuality of friction ridge skin. Empirical studies of fingerprint persistence have shown that friction ridge arrangements do not change with time, barring the formation of a scar resulting from damage or injury severe enough to disrupt the friction ridge template located at the basal layer of the epidermis (Faulds 1912; Maceo 2005). …