Examination Of Fingerprints

STANDARDS FOR EXAMINING FRICTION RIDGE IMPRESSIONS AND RESULTING CONCLUSIONS
(LATENT/TENPRINT)
(To Replace: Friction Ridge Examination Methodology for Latent Print Examiners, ver. 1.01, and Standards for Conclusions, ver. 1.0)

Preamble
Friction ridge impression examinations are conducted by examiners using the Analysis, Comparison, Evaluation, andVerification (ACE-V) methodology, which includes both qualitative and quantitative aspects. ACE is not generally applied as a strictly linear process because it may include a return to any previous phase. Application of ACE includes observations, measurements, assessments, decision-making and documentation, which are enabled by the education, training, skill, and experience of the examiner.
Theexamination of friction ridge impressions and the resulting conclusions are based on ridge flow and ridge paths; the location, direction, and spatial relationships of minutiae; and ridge structure. The analysis phase leads to the determination of suitability. Following comparison, the evaluation phase leads to the following conclusions: individualization, exclusion, or inconclusive. Theseconclusions are based on the following premises [1] [2]:
• Friction ridge skin bears an extremely complex, unique and persistent morphological structure.
• Notwithstanding the pliability of friction ridge skin, the contingencies of touching a surface, and the nature of the matrix, an impression of friction ridge skin structure may be left following contact with a surface.
• This impression may displayfeatures of varying quality (clarity of ridge features) and specificity (weighted values and rarity).
• Notwithstanding variations in clarity and specificity, the unique aspects of friction ridge skin may be represented as highly discriminative features in impressions.
• An impression that contains sufficient quality and quantity of friction ridge features can be individualized to, or excludedfrom, a source.
• The use of a fixed number of friction ridge features as a threshold for the establishment of an individualization is not scientifically supported.


1 Scope
1.1 The ACE-V methodology of friction ridge impression examination utilizes a qualitative and quantitative assessment of Level 1, Level 2, and Level 3 details.
1.2 The ACE-V methodology is applied to examinations andcomparisons of friction ridge impressions. This document illustrates the case of unknown to known comparisons but is applicable to other comparisons (e.g., known to known).
1.3 The application of the ACE-V methodology to casework requires examiner competency as established through training and testing [3].
2 Factors Affecting Examinations
The following factors affect the qualitative andquantitative aspects of friction ridge impressions. A competent examiner [3] will understand these factors, recognize that they occur in friction ridge impressions, and understand how they influence friction ridge impression reproducibility. These factors may cause an apparent dissimilarity between impressions from the same source. Failure to properly assess the occurrence and influence of these factorscould result in misinterpretation. When applicable, the following factors must be considered in all steps of the ACE-V methodology:
• Anatomical aspects include the condition of the skin (e.g., scars and warts) and the morphology of the hand and foot relative to the shape and contour of the substrate.
• Transfer conditions include pressure applied during transfer, slippage or twisting, sequence ofdeposition (i.e., double taps and overlays) and an understanding of the limitations of friction ridge pliability.
• Transfer media include bodily secretions and contaminants (e.g., sweat, blood, paint, dirt, oil, grease).
• Detection techniques that can be one or more of the following: optical (i.e., light sources and illumination techniques), physical, or chemical processing techniques.
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