Difference in Friction Ridge Features
Some loss/discrepancy of detail in the quality and quantity of information depicted by the friction skin features in both the unknown latent print impression and the known print is expected. The deposit of the latent impression is never expected to capture and depict all the quality and quantity of friction ridge skin features that exist in the known print. Knowledge of this issue provides the basis for the practice of incorporating limits for Tolerance in the comparative process.
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 the cause for any difference is attributable to 'distortion', then the 'artifact' created by such distortion 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.
However, if the cause for 'difference' cannot be attributed to some recognizable, visible 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 undisputed genuine discrepancy in the friction ridge features, and is cause for the declaration of an Exclusion.
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 the cause for any difference is attributable to 'distortion', then the 'artifact' created by such distortion 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.
However, if the cause for 'difference' cannot be attributed to some recognizable, visible 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 undisputed genuine discrepancy in the friction ridge features, and is cause for the declaration of an Exclusion.