IAI Approved Training

Distortion Title 2

Please note this workshop is now taught as a three-day workshop!  Why? Because Alice has upgraded her camera equipment! She is excited to bring participants new exercises and videos (4k videos!), live distortion demonstrations, and more time on the most troublesome latent prints (tonally transitioning prints)!

The three-day workshop cost is $425 per person. Please note registration fees will be adjusted to accommodate taxes if applicable. For inquiries outside of the United States or Canada, please contact the instructor at Alice@EvolveForensics.com.

Host agencies receive a 10% discount for all host agency registrations!

This three-day workshop focuses on the Analysis phase of the ACE-V (Analysis, Comparison, Evaluation, Verification) process. During the Analysis of a latent print, the analyst is gathering information. The analyst is detecting the features they may use during the comparison, setting tolerances for variation in appearance, and determining the utility of the print. The ability to detect these features in the latent print and the establishment of tolerances for variation in appearance are inextricably linked to the distortion present in the latent print.

Biological Distortion

Any discussion of friction ridge impressions starts with the friction ridge skin. What features does it have? What is the structure of these features? Which features are variable in the population and which features are common? How and why do these features vary in appearance from impression to impression? What does normal versus abnormal friction ridge skin look like? What happens during wound healing that causes a scar? Participants will study images of the skin displaying various developmental issues (e.g. congenital ridge hypoplasia and dysplasia) and alterations of the friction ridge skin (e.g. aging and scarring).

Contact Distortion

The skin is a flexible medium that distorts when it touches a surface and displaces residue when it moves across a surface. The movement of the skin on the surface causes predictable effects on the ridges and furrows that are easily recognizable. Attendees will analyze the distortion effects of latent prints placed on glass under controlled conditions. After analyzing the latent print, the attendees will observe the actual video of the latent print being deposited onto the surface.  Attendees will be provided a different paradigm with which to consider distortion: how the skin leaves an impression. For many, this is a shift from trying to decipher a latent print based on what is expected in the known print.

Residue Distortion

Residue distortion refers to how the following affect the appearance of the ridges and furrows in a latent print: 1) type of residue, 2) placement of residue on the surface of the skin, and 3) transfer of residue to a surface. This section of the course focuses on the most difficult of visual distortion effects: tonally transitioning ridges.  Examples of tonally transitioning ridges and the causal affects are demonstrated and discussed. Attendees are provided alternative strategies for following ridges through tonal transitions.

Surface Distortion

Textured surfaces can introduce problematic background noise or create false edge shapes and pore structure. The shape of the object and the natural handling can cause unexpected finger height distributions in simultaneous impressions. Additionally, any impression where the hand and fingers are grasping an object will have clusters of minutiae in unusually close proximity when the clusters are separated by a primary flexion crease. Examples of the distortion effects of different types of surfaces will be demonstrated and discussed with attendees.

Analysis Phase of ACE-V

The analysis of a friction ridge impression answers two questions: 1) is there sufficient information to warrant a comparison and 2) what search parameters will be assigned to the print (where and how to look in the exemplar prints). The information in friction ridge impressions used to answer these questions will be explored.