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HOW MANY POINTS DO YOU NEED & OTHER QUESTIONS ASKED BY IGNORANT ATTORNEYS TRYING TO RATTLE YOUR CAGE
by THOMAS W. JONES, CLPE Q. How many points do you need to make a comparison? A. A sufficient number to reach a conclusion. There is no set number. Q. If there is no set number what is the basis for forming an opinion? A. When I am comparing prints I locate an area of clarity shared by both the latent, or unknown print, and the file print. Then, within that area I locate a group of points in relation to some common `landmark'. I look for that same group, in the same location, using the same `landmark', on the file print. Having located the group of points in the same relationship to each other as those found in the unknown print, I begin matching other adjacent points until I am convinced that both prints were made by the same area of friction skin. Q. Well, how many points do you need to form an opinion? A.I have answered that question before, but let me explain “Points” and clear up any misunderstanding about how it works. On very clear prints it is usually sufficient to compare the gross `points', which are ridge ends and the points at which two ridges join. A group of these `points' is sufficient to allow a study which leads to a positive conclusion. If the ridges end or join together in an area where such things are common, such as a triradius, pattern core, or the underside of a plain whorl, they will carry less decision--making weight than they would have if they occurred in an otherwise clear area where there is no physical reason for them to end or join. On prints that present fewer points, because of limited areas of mutual clarity between prints being compared, it is sometimes necessary to use the second level of details which are ridgeline anomalies. These are created by misplaced or misaligned ridge units causing breaks in the ridge, or bulges, or angular attachments . These anomalies, in relation to a particular ridge end or joining, and when found in both prints, are extremely valuable in the formation of a conclusion. Q. Aren't there some agencies that require a certain number of points? A. None that I know of. The California Department of Justice requires that if an examiner makes a positive based on eight or fewer points it must be reviewed by a supervisor. No knowledgeable Latent Print Examiner would make such a requirement. If an Administrator insists upon a minimum, it is out of ignorance. Furthermore, if such a requirement was in place the net effect would be to absolve an amateur of blame in an erroneous identification as long as the point number requirement had been met. There is no scientific requirement for any set number of “points” in order to reach a conclusion of “same source”. This is the position of the International Association for Identification, and was the conclusion of a group of the worlds foremost experts during a recent symposium held at Ne'urim, Israel, and is something I have known for years from my own experience. Q. How many points did you find on this comparison before reaching a positive conclusion? A. I didn't count them because it has no value. I examined both the latent and inked prints and compared them. I found a group of points that, in my mind, was unique in arrangement, and then found that same group on the file print. It is the relationship of points in a group which makes one area of friction ridges different from any other. Q. Could you show me which points you used in this comparison? A. When I make my comparisons it is in a controlled setting, in my office, with adequate lighting and magnifiers. I have completed my examination and reached a conclusion. If you are interested in the exact details then you will have to come to my office and I will gladly go through the entire laborious process with you. Q. Could you have made the positive with one less point? A. No. Q. Could you make a comparison with seven points? A. I would have to see the prints in question, and examine them, in order to tell you how many points it took to reach a conclusion. Q. Could you reach a positive conclusion with just one point? A. I would have to see the prints in question and examine them. The point that you are missing is that each area of friction skin is unique and therefore each comparison study is unique and therefore to know, in advance, the requirements for reaching a conclusion is impossible! Q. Didn't the FBI, at one time, have a requirement of twelve points? A. According to a letter from John Edgar Hoover to the New York Police Department in 1958, the FBI policy of requiring twelve points was discontinued “a number of years ago". The letter goes on to say that “experience, acquired through many years of handling millions of fingerprints, has shown that positive identification can be made on less than twelve points. Each case is decided individually. Weight is given not only as to the number of points, but also as to their clarity, type, and relation to each other.” Q. You have explained that latent prints are, by their nature, usually incomplete and not always clear. How do you know that there are not contradictory points in that part of the print that you can't see? A. We are able to identify any area of friction ridged skin which contains sufficient ridge detail to complete the study. It is not necessary to examine a print of the entire hand in order to positively identify one finger or even part of one finger. It is not possible to positively identify a partial print and have a negative finding on any other piece of latent from the same finger. Q. But you have said that one unexplainable difference would end the study, that it could not be a match. How do you know there isn't an unexplainable difference on that part which is missing. A. There cannot be an unexplainable difference in any other area of a print which has been compared and found to be the same. Q. How sure are you that those two prints were made by the same finger. A. Absolutely sure! I don't testify to probabilities. Q. Have you ever made a mistake? A. If you are referring to a mistake in a friction ridge comparison, the answer is NO! There is too much riding on my examination and finding. In addition to my own efforts to avoid errors there is a policy that all examinations be verified by another, qualified, Latent Print Examiner. Q. Was that done in this case? A. Yes. [The preceding Q & A article was a handout given to all of Tom's latent print examiners along with the following information which provides some additional insight and wisdom.] Subject: Testimony Hang-ups -- Points Continuous worrying about Defense Attorney questions and how to answer them is a cause of unnecessary anxiety and stress. It's important to remember that you are not required to dream up a stupid answer to a stupid question. If you know what you are doing and have adequate reports of what you have done, there is nothing they can ask which should pose a problem to you. If the question has nothing to do with reality, you can ask that it be rephrased or tell the Attorney that the question is gibberish. If you are going to testify as an expert, you should be an expert, and know those things about which you claim expertise. If you suffer from stage fright, you will still be all right if you know what you are talking about. There is nothing I can do about your stage fright, but I can help you formulate answers that would make it appear that you know what you are talking about. One thing is for sure — the time to learn is now, while you are not under pressure — not on the stand or after you have been made to look like a fool.
[Ed--—Tom's knowledge and wisdom mixed with his witty style provides an
outstanding discussion which relates to the lead article in this issue
“Professor Claims....” Thanks Tom!!!
This article was printed in “THE PRINT” |