Sample from FBIS on-line training

1. THE SCIENCE OF FINGERPRINT IDENTIFICATION- Friction Ridge Identification is generally understood to be the individualization of the ridge detail found on the end joints of the fingers, since those areas are taken for record and/or filing purposes. The technique of identifying fingerprints is equally applicable to identifying any of the other ridged areas of the hand or foot Module # 6

2. Visual Component of Identification When a human looks at a number, letter or other shape, neurons in various areas of the brain’s visual center respond to different components of that shape, almost instantaneously fitting them together like a puzzle to create an image that the individual then “sees” and understands. The eye lens, is perfectly clear, perfectly curved and is capable of focusing on an incredible amount of data. But vision is only partly to do with the retina, lens, and cornea. Understanding what we see, happens in the brain, which is why a person with perfect vision is still susceptible to optical illusion. Our visual nervous system approximates color, shape, and dimension. The process of seeing begins with the presence of light, an image formed on the retina, and an impulse transmitted to the brain, but there are many other factors that play a part in how we perceive visually. Our perceptions are influenced by our past experiences, imagination, and associations. In a tenth of a second, we can recognize something we see as an animal or not. Studies show this immediate, rough impression probably depends on recognizing just one or more individual parts of what we see. Fine discriminations – such as recognizing individual faces – take longer to happen, and the studies suggests that this delay depends upon emerging signals for combinations of shape fragments. The brain has to construct an internal representation of an object from disparate pieces.”

3. Let’s have a little Fun In the image to the right you could interpret it as a portrait of an older man, but when you look closer you’ll see a number of faces, images and silhouettes of faces. Why does our mind interpret the images we see in this way? The simple explanation is our mind assimilates the image we see and compares it with information already stored in our brain. In a recent Cambridge University study it was found that as long as the 1st. and last letters in a word were correct it didn’t matter if the other letters were mixed, a person could still read the paragraph or sentence correctly interpreting what the writer meant. An example of how our perceptions are influenced by our past experiences, imagination, and associations which can create a dilemma when doing fingerprint comparisons. It is critical you are objective when doing your analysis and evaluation of ridge detail, you cannot expect to see something based on past knowledge/experience. You have to work at being completely objective. The best way to accomplish an unbiased comparison is by following the analysis, comparison, evaluation and validation procedure.

4. Objective Analysis When doing a fingerprint comparison your going to be asked to make an objective decision based on what you see in front of you and not be influenced by subjective reasoning. The brain will attempt to assist you in recognizing images, it could give you a perception of something that is not there. How many of us read A Bird in the Bush, not noticing THE is repeated

5. Fingerprint Examiners are allowed to make positive identifications with: Appropriate Training Appropriate Experience Appropriate Ability Following agency policy. There is not a required minimum number of minutiae required for an experienced examiner to individualize a fingerprint comparison. Individual agencies may have policies and procedures on what they feel constitutes an individualization. In this training course I will require 12 points for identification, similar to Locard theory on identification. Requiring a set number of minutiae is a training aid, to insure the student understands the value of minutiae along with gaining experience in minutiae analysis/comparison. The individuals taking this course may have no or limited experience in the individualization of friction ridge detail. The average fingerprint contains between 75 and 150 points of identification and since we will be dealing with mostly very good images, a 12 point minimum will work well. I would encourage students during the training to exceed the minimum the course requires.

6. The Verification Process The process of making a fingerprint comparison between a search fingerprint image and the suspect fingerprint image. Whether you are doing a comparison of one (1) image or multiple fingers the process is always the same: Analysis Comparison Evaluation In latent fingerprint comparisons and most state ten print systems there is also a: Validation process

7. Referred to as the Scientific Method of fingerprint individualization. Analysis – the qualitative and quantitative assessment of Level 1, 2, and 3 detail to determine their proportion, interrelationship and value to individualize. Comparison – to examine the attributes observed during analysis in order to determine agreement or discrepancies between two friction ridge impressions. Evaluation – the cyclical procedure of comparison between two friction ridge impressions to effect a decision, i.e., made by the same friction skin, not made by the same friction skin, or insufficient detail to form a conclusive decision. Validation- It is highly recommended that all fingerprint identifications be validated by 2nd. examiner or electronically in an AFIS. Note: Many state agencies do not require a 2nd. verification on ten print identifications of arrest/applicant cards. Larger states and the FBI do require a validation ( 2nd. Verification). A second verification may be done by a qualified fingerprint examiner or possibly electronically, using lights out technology. The single verification makes a system vulnerable to identification errors.

8. EVALUATION Suspect Image Search Image

9. Area’s of concern when comparing possible identifications #1 As every examiner knows, search and exemplar (database) images are never exactly the same. The reasons are many; how the exemplar was recorded or temporary or permanent damage to the fingers, etc. The fingerprint examiner during the analysis and evaluation must be able to understand and explain any discrepant points found in either the search or exemplar images. The 1 discrepancy rule , if there is 1 unexplainable discrepancy in either the search or exemplar image an individualization cannot be made. These images are from the same card the rolled and plain impression of the right thumb.

10. Area’s of concern when comparing identifications #2 The 2nd. major area of concern is suspect images produced in today’s automated fingerprint systems often have very similar constellations of points of similarity. Despite the unusual similarity in the relationship between points in many prints, the prints may not be identical fingerprints. The enormous size of today’s AFIS databases and the power of the search algorithms can find a confusingly similar print to the one being searched. As databases increase and algorithms improve, there will be more suspects produced, that will have unusual similarity between points but will not be the individuals print. So can this type of error be prevented ? The answer is “yes” we can minimize the numbers of these type errors with good training and adherence to procedure.

11. Area’s of concern when comparing possible identifications #3 The 3rd. Area of concern is when an examiner uses "backward " reasoning. In effect allowing yourself to be influenced by the search print in effect by working backward from the suspect print. The examiners will find features in the print being searched and then look for them in the image being searched. The danger is in poor quality images murky or ambiguous points may be erroneously identified. When an examiner is dealing with a poor quality latent that lacks clarity, it is tempting to look at the exemplar and work backward but it can have disastrous results.

12. Area’s of concern when comparing identifications #4 To much reliance on Level III detail. Level III detail can include a number of things from ridge shape and pores to scars and this information can be beneficial in individualization when properly used. In ten print searches this should not be a big issue because the clarity and amount of minutiae available is significant. While level III detail can be helpful, it becomes less helpful as clarity decreases. I have seen cases where the ten print image or suspect images are so poor that you in effect are making a comparison very similar to a latent comparison and Level III detail may be required to effect an identification.

13. Area’s of concern when comparing identifications #5 In an AFIS search the examiner is given two (2) search and two (2) target images. While the examiner may be tempted to identify based on level 1 similarity between these four (4) images, this could result in an erroneous identification. The examiner must utilize the analysis, comparison and evaluation steps.

14. DISTORTION CAUSED BY SCAR1st. glance the images look dissimilar but look in the delta area.