2022 03 Difficult Latent Print Comparisons - Dublin, CA



March 21 – 25, 2022


0800 – 1700 Monday – Thursday
0800 – 1200 Friday


Alameda County Sheriff's Office
Lake Merritt Conference Room – 3rd Floor
3 Park Place
Dublin, CA 94568

Alameda SO Contact

Jennifer Quan
Email: JQuan@acgov.org

Instructor Contact

Alice White
Email: Alice@EvolveForensics.com
Mobile: 702.769.9469

Hotel Information:

There are many hotels in the area – take your pick!

Download Class Flyer: Difficult Latent Print Comparisons

Please bring loupes and ridge counters to perform the comparison exercises. Each attendee receives two notebooks with the course. One notebooks contains the lecture content and “unknowns”, while the second notebook contains the exemplar finger and palm prints for comparison.

The examination (ACE) of friction ridge impressions is rooted in two arenas: 1) the magnitude, variation, and hierarchical nature of the features available in the impressions and 2) the heuristics examiners use during the examination process. These heuristics are developed through training. An examiner who exhibits high accuracy assigning search parameters is expected to be more efficient in the searching process because the examiner can quickly narrow down the possible donor areas that must be compared. Highly skilled examiners are also expected to recognize when the macroscopic features are uninformative (e.g., when the shape of an impression is dictated by the surface rather than the hand), ambiguous (i.e., impression that must be searched in multiple regions, right and left hands and feet, or multiple orientations), or conflicting (e.g., ridge flow/patterning indicates one orientation, but the creases indicate another). The ability to effectively assign search parameters is inherently linked to exclusion decisions. If a latent print cannot be reasonably assigned to a given anatomical region, then complete friction ridge exemplars of all the friction ridge skin should be requested and multiple anatomical regions and orientations compared before reporting that the friction ridge impression was excluded from a particular subject.

This 4 1⁄2 day workshop, taught by Alice White, introduce all regions of the friction ridge skin with a focus on the similarities and differences in shape, size, creases, patterns, deltas, ridge flows, ridge counts, ridge lengths, ridge thicknesses, and ridge curvature. Building robust regional mental models should increase comparison efficiency via faster recognition of the various parts of the hands and feet and decreases risk of error by recognizing the appropriate conditions to widen search parameters (check other regions of the skin or alternative orientations). A thorough understanding of the skin will also permit better assessment of the completeness of exemplar prints – has every region I need for this comparison been recorded in the exemplars? Comparison exercises will promote the recognition of ambiguity in diagnostic search information and incomplete exemplars, emphasizing appropriate inconclusive and exclusion decisions. We will also discuss the benefits and limitations of written procedures that may help facilitate the decision- making process.

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