Preamble

The documentation of a fingerprint examination may include contemporaneous notes of the overall impression, e.g., substrate, matrix, development medium, pressure distortion markers and so on.  The quantity and quality of the information present will dictate the extent of this documentation. 

However, fingerprint examination documentation should not be limited to a sweeping, general view regarding the overall impression, but it should also include the interpretation of ridge feature shapes in position, the assessment of their clarity, reliability and quality of agreement with it's exemplar counterpart, the examiner's best estimate (based on subjective and/or empirical probability modeling) of its aggregate quantitative-qualitative value or "T-Value" and most importantly the best estimate for the number of close matches or "look-alikes" likely to exist in the relevant fingerprint population for the case at hand. 

See Validation Study for a comparison between "best estimates" by latent print examiner professional judgment and the T-Model for numbers of close matches likely to be present in a fixed fingerprint population group.

With regards to the documentation of the analysis, comparison and evaluation of fingerprint material, it is significant to note that conventional “ACE-V Methodology”, which utilizes only  professional judgment, has been described by the National Academy of Sciences as an invalid tool to make reliable fingerprint conclusions [91].  Furthermore, the original definition of the word "verify” means "to validate, to authenticate, to prove true”.  It is not possible to validate, authenticate or "prove the truth" of a latent or unknown print identification. 

Examiners can only agree or disagree with the findings of another examiner, but they cannot make a determination with certainty that a particular person is in fact the source of a latent print impression.  There is always a chance the examiner can be fooled by a fingerprint look-alike, e.g., Brandon Mayfield.  There is always a chance for human error. 

As a result the application of the term "verification" to define the strength of fingerprint evidence is fundamentally misleading and exaggerates the significance of fingerprint evidence.

Historically, the term "ACE-V" was adopted in an attempt to reflect good science and the scientific method.  However, conventional ACE-V fingerprint methodology (e.g., the no minimum amount standard of corresponding ridge detail needed to infer positive identification or exclusion) fails to prohibit conclusions.  For example, based on this ACE-V method, fingerprint conclusions have no thresholds for sufficiency to infer positive identification, which means positive identification can be based on any amount of matching ridge features.  As a result, it is not prohibitive.  Only a true scientific theory is prohibitive [92][93].  The ACE-V fingerprint method lacks this important criteria. 

It is significant to note here that SWGFAST latest definition for the "V" in ACE-V, e.g., verification [95], as "The final step of the ACE-V method. A review and independent analysis of the conclusion of another examiner", fails to speak to the root meaning of the word "verify", e.g., "to prove the truth of", and is inconsistent with basic dictionary definition.  Instead, it describes the simple process used to either corroborate or refute, e.g., agree or disagree with, the initial conclusions made by the first examiner.  

It is important for examiners to understand the fact that all knowledge is provisional, conjectural, hypothetical - we can never finally prove our scientific theories, we can merely (provisionally) confirm or (conclusively) refute them [Karl Popper].  This simply means when a fingerprint examiner makes an identification, for example, a second examiner can only agree or disagree with it; he cannot prove the truth of it. 

The word "verification" implies a much greater strength for the evidence than what is possible, and therefore, the term is misleading and an exaggeration to the trier of fact.  A more appropriate term is simply "review" or "check".

ACE-ACE

A more accurate description for the practice of fingerprint examination may be described as simply "analysis, comparison, and evaluation" with the term "verification" discarded, and replaced, for purposes of review, e.g., quality assurance, with another independent "ACE". 

Currently, fingerprint examination is based on professional judgment (subjective probability) and/or empirical probability modeling (e.g., T-Model, Neumann Model [96], etc.), and only for purposes of quality assurance e.g., to reduce the chance for error, is the independent examination of fingerprint material by two examiners (a.k.a. ACE-ACE) ever truly needed.

It is significant to note that documentation of the examiner's best estimates for numerical match probability or the quantitative-qualitative value of ridge features (and how they compare to the best friction ridge look-alikes ever seen, speaks to the need for a "probabilistic approach" to fingerprint examination, the issue of “clarity” (see NAS Report [91]) as well as issues raised regarding the need to elaborate on "sufficiency", e.g., Maryland v. Rose [55] [56] and Illinois v. Safford [94].

Document Ridge Features Relied Upon to Make Conclusion

The ridge features relied upon during comparison may be marked in photographic enlargements of the latent v. exemplar with the quantitative-qualitative description for each that includes annotation for the following:

• Ridge Feature Number (e.g., 1, 2, 3, etc.)
  
• Ridge Feature Shape (e.g., ending ridge unit, core area, scar, etc.)
• Ridge Feature Position (e.g., intervening ridge count to nearest neighbor)
• Ridge Feature Clarity/Reliability Grade (e.g., A, B, C, etc.)
• Ridge Feature Quality of Agreement Grade, e.g., A, B, C, etc.)

Example

A hypothetical fingerprint feature is documented as "7E2A" during the analysis stage of an examination and represents the following:

"7" = Ridge feature no. 7 (this is used to correlate corresponding ridge features in the latent v. exemplar)

"E" = Ending ridge unit (quantitative weight of 14.25 - ending ridge is not in a funnel area)

"2" = 2 intervening ridges to nearest neighbor (quantitative weight of 2.5)

"A" = Clarity/reliability grade of "A" (no reduction factor)

As a result the aggregate quantitative-qualitative value, e.g., T-Value, for this one corresponding ridge feature in a latent v. exemplar is estimated as follows:

(14.25)(2.5)(1)= 36.625

During the comparison stage of the examination, if the quality of agreement between the ridge feature in the latent  v. exemplar is assessed as "above average" or assigned a "B Grade" of .75, then the T-Value, e.g., reciprocal of the match probability, is reduced.  This change may be documented as follows:

Ridge feature "7E2AB" 

which is mathematically expressed as follows:

(14.25)(2.5)(1)(.75) = 26.7

T-Value 26.7 represents the reciprocal of the match probability for this single corresponding ridge feature present in the latent v. exemplar.

Each corresponding ridge feature in the latent v. exemplar that the examiner relied upon to make his/her conclusions are documented in similar manner.  The T-Values for each ridge feature are multiplied (e.g., product rule) and the aggregate T-Value for the total arrangement of ridge features is then compared to the relevant population for the case at hand in order to determine sufficiency or insufficiency to infer positive identification.

The author supports, in part, the standards proposed by SWGFAST for the documentation of friction ridge analysis (CLPEX July 27, 2009), however with the following revisions:

When friction ridge detail is examined, the examiner’s documentation should be such that another qualified examiner can determine what was done, if needed*.  Documentation should be made at or near the time of the examination and could be in the form of annotated images, narratives, worksheets, annotated legible copies, sketches, AFIS or other electronic system records, or any combination of these methods. This documentation should be a part of the case record.

1.    Analysis

1.1  Latent Prints

1.1.1  The presence of friction ridge impressions, including those that are of no value for comparison, should be documented.

1.1.2  Analysis documentation of the latent print should be completed prior to comparison. 

1.1.3  At a minimum, the following should be documented in the case record:

• Presence of ridge detail usable for comparison and/or identification
  
• Relevant population for the source of the latent, e.g., conservative upper-bound plausible number of people who could have committed the crime at hand (e.g., local population, county AFIS database, state AFIS database, national AFIS database, etc.).
• Best conservative estimate of the discrimination power for the aggregate amount of ridge detail present in the latent based on relevant population for the case at hand (e.g., no value for comparison, no value for identification, usable for comparison, usable for identification, estimated T-Value, estimated match probability, and/or estimated number of look-alikes in the population group for the case at hand)
  
• Preservation method (e.g., lift card, photograph, digital image, legible copy)
• Level of confidence for the discrimination power of the latent (e.g., high, very high, borders on certainty, numerical confidence interval, etc.)
  

1.2  Known Prints

1.2.1  Documentation of known prints is necessary if comparisons will be conducted. At a minimum, the following should be documented in the case record:

• Unique identifier of the exemplar such as name, date of birth, assigned identification number, or reference to the specific exemplars (e.g., date of arrest, date of recording).
• Anatomical aspect(s) represented in the exemplars (fingerprints, palmprints, or footprints)
• Medium (e.g., ink, livescan)
• Origin (e.g., printed from archive, direct submission)
  

1.2.2  Known prints that are deemed insufficient for comparison or that contain any factors which may affect the comparison should be documented.  These factors may include:

• Incomplete recording of the friction ridge skin
• Missing anatomical aspects (e.g., palms, phalanges)
• Unclear recording of the friction ridge skin
  

2.  Comparison

2.1  The quantity and quality of ridge features compared and the level of agreement and/or non-agreement found in each should be documented.

2.2  At a minimum, a legible copy of the known print should be retained.

2.3  If additional analysis of the latent print occurs, supplemental notes should be added and dated.

3. Evaluation

3.1 Documentation for inference of identification should include:

Best estimate of the discrimination power for the aggregate amount of corresponding ridge detail present in the latent v. exemplar based on relevant population for the case at hand (e.g., amount of corresponding ridge features exceeds largest and best amount ever seen in a non-match and/or amount bears an aggregate value, e.g., T-Value, that exceeds the relevant population group for the case at hand).

Quantitative interpretation and qualitative assessment of ridge features used to infer positive identification.

Specific latent friction ridge impression examined

• Unique identifier of the exemplar(s) used to reach the conclusion
• Anatomical aspect (e.g., right thumb, left palm)
• Initials, signature, or equivalent (e.g., unique identifier, electronic signature) of examiner
• Date conclusion reached
• Level of confidence in the inference of identification should be documented (e.g., borders on certainty and/or numerical confidence interval)
  

3.3  Documentation of an exclusion shall include:

Best estimate of the discrimination power for the aggregate amount of non-corresponding ridge detail present in the latent v. exemplar based on relevant population for the case at hand (e.g., exceeds largest and bast amount of non-corresponding ridge features ever seen in a match).

Quantitative interpretation and qualitative assessment of ridge features used to infer positive exclusion.

Specific latent friction ridge impression examined

• Unique identifier of the exemplar(s) used to reach the conclusion
• Anatomical aspects
• Initials, signature, or equivalent (e.g., unique identifier, electronic signature) of examiner
• Date conclusion reached
• Levels of confidence to infer identification should be documented (e.g., borders on certainty and/or numerical confidence interval) 
  

3.4  Documentation of an inconclusive should include:

Specific latent friction ridge impression examined

• Unique identifier of the exemplar(s) used to reach the conclusion
• Reason (e.g., better exemplars needed, specific anatomical aspects needed, insufficient quantity and/or quality of detail in agreement or disagreement, etc.)
• Initials, signature, or equivalent (e.g., unique identifier, electronic signature) of examiner
• Date conclusion reached
  

3.5  Conclusions should be documented prior to the examination by another examiner(s).

4.  The independent examination by a second examiner is recommended for purposes of quality assurance and to reduce the chance for error.

5. Consultations

Consultations should be documented and should include:

• Specific friction ridge impression reviewed
• Nature of consultation (e.g., discussed distortion in core)
• Initials, signature, or equivalent (e.g., unique identifier, electronic signature) of examiner(s)
• Date of the consultation
  

Refer to SWGFAST for updates regarding recommended documentation of friction ridge examination.

"Every good scientific theory is a prohibition:  It forbids certain things to happen.  The more a theory forbids, the better it is."

Karl Popper, Conjectures and Refutations