CLPEX Chat Board

Just kicking this out there as speculation and comments.


A Model for Comparative Analysis

4.3.1 The identification process will pass through several phases during the
course of an examination.
• These phases are not static but fluid with movement back and forth between phases in some examinations.

4.3.2 The First Phase:
• This first phase can be referred to as the analysis or evaluation stage.
• The first phase starts with a neutral position to maintain objectivity.
• The questioned item is studied without any knowledge about the known item.
• The data is detected and evaluated in the most objective manner.
• The questioned image is examined and basic questions answered.
o Is the questioned image made from friction ridge skin?
o Is the questioned image suitable for comparison?
o If the answer to either question is “No” the examination is concluded.
• The area of questioned friction ridges is examined and basic tasks completed.
o Ridge flow is recognized and noted.
o Image is orientated according to information presented.
o Relevant distortions are recognized and accounted for.
o A distinct target or anchor group is chosen and its unit relationship memorized.
• The area of known friction ridges is examined and basic questions answered.
o Is the representative area in the known print recorded?
o Is the representative area reasonably free of distortion?
o If the answer to either question is “No” a different exemplar or target group is chosen.

4.3.3 The Second Phase:
• This second phase can be referred to as the comparison phase.
• The properties of the unknown area of friction ridges, established during the first phase, are compared to the known area of friction ridges.
• The second phase starts at the area recognized and with the target group selected during the first phase.
• The minutiae selected are compared as to their location, shape and relative position to each other.
• The second phase progresses systematically and sequentially until all available ridge detail has been compared and events shared by both images is accounted for.

4.3.4 The Third Phase:
• This third phase can be referred to as the evaluative, decision, or opinion stage.
• Similarities in the ridge structure will each have a specific value or weight that is applied toward establishing the source of the friction ridges.
• Are dissimilarities present and within tolerance?
• Are “True” discrepancies present or are they an effect of distortion?
• After assessing the data present or absent in both images a conclusion is reached.
• The conclusion is subjective and is dependent upon the training, experience, talent, motivation, and daily variables of the Latent Print Examiner.

This looks great at first blush. I'm going to print it out and think on it some. I like the way that you describe the "evaluate" phase - it's more descriptive than the explanation that I have been using.

C

A couple of suggestions for consideration:

Charles Parker wrote:A distinct target or anchor group is chosen and its unit relationship memorized.

• Change to: "One or more distinct targets or anchor groups are chosen and their unit relationships memorized."
  
  I know that I frequently find two or even three target areas if available. If true to analysis of the questioned print first, we don't know the quality, or what areas may be smudged or otherwise distorted in the known. More than one option can increase both efficiency and accuracy.

Charles Parker wrote:Similarities in the ridge structure will each have a specific value or weight that is applied toward establishing the source of the friction ridges.

• Possibly change this to: "Similarities in the ridge structure will each have a variable value or weight that is applied toward establishing the source of the friction ridges."
  
  This is a tough one to quantify, but my thinking is that the value or weight of an individual characteristic may change depending on pattern type, specific placement and relationship with other characteristics, clarity, and/or other factors.

Regards, RLT