Factors such as pressure and distortion may change the appearance of, or may create an "artifact" amongst, some friction ridge features. An assessment of any Distortion existing in the unknown latent print impression is performed in the Analysis phase.

 

This is an assessment of an area of friction ridge features in the unknown that is taken into consideration in the anticipation of finding apparent differences in the appearance, and sometimes arrangements, of the friction ridge features in the corresponding area in the known print. A friction ridge feature that appears as a ridge ending in the latent print may later appear as a bifurcation in the known print. The examiner must study any Distortion which is present in order to determine its cause, and the related influence on the appearance of the friction ridge features.

 

The use of techniques such as ridge counting and ridge tracing performed with respect to other friction ridge features in the immediate vicinity is helpful to understand the cause and nature of the dissimilarity. If distortion is the cause of the discrepancy, then the presence of an "artifact" would be within an examiner's tolerance for differences. These artifacts are simply appearances of the friction ridge features that are not exactly the same between the known and unknown impressions (i.e. Distortion).

 

Causes of Distortion include:

• Receiving Surface/Substrate influences.

• Pressure & Touch impact during Deposition.

• Elasticity of the skin.

• Adverse Matrix/Residue reactions.

• Adverse Reagent/Residue reactions.

• Poor condition of the friction skin.​

 

If the cause for the 'difference' cannot be attributed to some contributing factor which can be recognized as Distortion, then the inability to identify the cause for the 'difference' lies outside the examiner's acceptable limits of Tolerance. The 'difference' is then regarded as a genuine disagreement in the friction ridge features, and is cause for the formulation of an 'Exclusion'.