Compare
The second stage of the process is comparison. Once the fingerprint officer has analysed the unknown mark and accumulated all the information possible it is then compared to a print on a fingerprint form.
Comparison of Patterns
Firstly the patterns are compared. The overall fingerprint pattern does not have sufficient uniqueness to determine an identification, and only functions to narrow the number of possibilities of donors. However, at this stage of the comparison, differences in pattern type may be sufficient enough to eliminate the unknown mark from the print.
Comaprison of Ridge Characteristics
If the patterns are found to be in agreement the comparison moves to the next level - the ‘comparison of ridge characteristics'. The ridge features are examined to ascertain whether they are in the same position, in the same order and have the same relationship to each other with none in disagreement in both the known prints and unknown marks. This is known as the coincident sequence.
If any unaccountable disagreement is found the identity cannot be established and the known print will be discounted from the comparison process.
However, if the initial sequences agree in both impressions, the expert will proceed to compare the relative position and location of further characteristics in both prints, all the time looking for any disagreement in the sequence of characteristics.
The fingerprint expert will also be taking into account the unique features of the ridges themselves looking for agreement between any visible distinctive ridge edge shapes and minute detail.
This process will continue unil the expert is satisfied that the comparison process is complete.