Interesting Tidbit 3
Posted: Sat Jun 30, 2007 6:11 am
I missed posting Tidbit 3 so I am correcting it today. The following is from a document by the IEEGFI which is the european equivalent of SWGFAST. If you have never read all of the IEEGFI documents I recommend that you do. You can access them with a Google Search. Interpol European Expert Group for Fingerprint Identification. I think they go into great deatil about Open Fields, the use of 2LD coming into an image Vs. those leaving an image. I would recommend every LPE to read their documents. Here is just a snippit from one of them.
1. Information or analysis phase
In this phase, the latent is studied without any knowledge about the comparison print. The information is detected, evaluated and validated in the most objective manner. Everything that is judged to be valid fingerprint information should be established here in order to be verified in the comparison print later. Distortions, superimposed prints and all other relevant observations should be made in this phase. This is the basis for an honest comparison, validation of similarities and possible explanation of differences. If, in the information phase, the print is judged to be unfit for identification, this decision should rarely be overruled later. If a decision is nevertheless overruled, this should be signaled, carefully discussed and well justified.
2. Comparison phase
The original latent and the quality and the quantity of the data found in the information phase are the starting point. Unbiased establishment of the facts is the aim. The potential for making a decision early in the comparative process must be recognized. The comparison must be an unbiased 'step by step' building process ensuring that the data in the latent and donor print agree with nothing in disagreement which cannot be logically explained (and accounted for). The decision must be made at the end of the process only.
Every single detail is checked as to whether location aspects and relations are similar to the detail in the corresponding locations of the comparison print. Differences should be detected, checked and noted. Any explanation of differences found should preferably be related to observations done in the information phase. All details are related to each other. Parts of a print that are distorted or damaged and show differences as a result of this distortion may be ignored if the distortion is consistent and demonstrable.
3. Evaluation or balance phase
In this phase, all facts are known and can be evaluated and validated. From all details, the similarity is validated; characteristic value and clarity are taken into account. The significance of the corresponding detail is validated. Differences are studied and are weighed whether they fit in the margins of tolerances normally found between prints coming from the same donor. Explanations for the differences are checked.
A minutia of which the location and direction are apparent in the latent and absent in the comparison print (or vice versa) in principle forbids the drawing of any positive conclusion on identity.
4. Conclusion phase
The found volume of similar information is measured against the standard that is in force. If that is met, or exceeded, the conclusion of identification is possible but not obligatory. The expert has to judge himself whether he/she is entirely satisfied and whether the conclusion of identity is solid and all risks excluded. If satisfied with the identification, the case should be passed on for verification. It is not proper (or acceptable), if in doubt, to leave the conclusion to the verifier, and to adapt/ accommodate to his/her opinion later.
1. Information or analysis phase
In this phase, the latent is studied without any knowledge about the comparison print. The information is detected, evaluated and validated in the most objective manner. Everything that is judged to be valid fingerprint information should be established here in order to be verified in the comparison print later. Distortions, superimposed prints and all other relevant observations should be made in this phase. This is the basis for an honest comparison, validation of similarities and possible explanation of differences. If, in the information phase, the print is judged to be unfit for identification, this decision should rarely be overruled later. If a decision is nevertheless overruled, this should be signaled, carefully discussed and well justified.
2. Comparison phase
The original latent and the quality and the quantity of the data found in the information phase are the starting point. Unbiased establishment of the facts is the aim. The potential for making a decision early in the comparative process must be recognized. The comparison must be an unbiased 'step by step' building process ensuring that the data in the latent and donor print agree with nothing in disagreement which cannot be logically explained (and accounted for). The decision must be made at the end of the process only.
Every single detail is checked as to whether location aspects and relations are similar to the detail in the corresponding locations of the comparison print. Differences should be detected, checked and noted. Any explanation of differences found should preferably be related to observations done in the information phase. All details are related to each other. Parts of a print that are distorted or damaged and show differences as a result of this distortion may be ignored if the distortion is consistent and demonstrable.
3. Evaluation or balance phase
In this phase, all facts are known and can be evaluated and validated. From all details, the similarity is validated; characteristic value and clarity are taken into account. The significance of the corresponding detail is validated. Differences are studied and are weighed whether they fit in the margins of tolerances normally found between prints coming from the same donor. Explanations for the differences are checked.
A minutia of which the location and direction are apparent in the latent and absent in the comparison print (or vice versa) in principle forbids the drawing of any positive conclusion on identity.
4. Conclusion phase
The found volume of similar information is measured against the standard that is in force. If that is met, or exceeded, the conclusion of identification is possible but not obligatory. The expert has to judge himself whether he/she is entirely satisfied and whether the conclusion of identity is solid and all risks excluded. If satisfied with the identification, the case should be passed on for verification. It is not proper (or acceptable), if in doubt, to leave the conclusion to the verifier, and to adapt/ accommodate to his/her opinion later.