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Monday, June 18, 2007

 
The purpose of the Detail is to help keep you informed of the current state of affairs in the latent print community, to provide an avenue to circulate original fingerprint-related articles, and to announce important events as they happen in our field.
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Breaking NEWz you can UzE...
compiled by Jon Stimac

Police Say Garbage Bag Fingerprint Broke Murder Case  SALT LAKE TRIBUNE, UT - Jun 15, 2007 ...a fingerprint lifted from a plastic garbage bag gave police detectives their break...

No Prints Found on Gun in Spector Case USA TODAY - Jun 13, 2007 ...expert testified in the record producer's murder trial that latent fingerprints rarely are found on guns...

Police Clear 26-Year-Old Murder Case  NBC 17-TV, NC- Jun 12, 2007 ...detectives requested that CCBI re-examine the fingerprint evidence collected during the initial investigation...

Forensic Science Gives Warfighters Edge BLACKANTHEM MILITARY NEWS, US - Jun 10, 2007 ...the Multi-National Corps-Iraq Forensics Laboratory has been enabling war fighters to track down criminals & insurgents throughout Iraq...

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UPDATES ON CLPEX.com


No major updates on the website this week.

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Last week

We started a series on latent print reporting, the process, conclusions and error.

This week

We continue the series through a discussion of the latent print process.  There are many decision milestones along the way that could cause an identification not to occur that could have occurred.  In general, we recognize these elements as common sense parts of the process, but I don't know if we really have a good idea about the extent of their effects.

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Latent Print Process Milestones and Missed Identifications
by Kasey Wertheim

Have you ever looked at the only print in the case and thought to yourself "if there were just a little bit more detail, I could do something with this..." and then further consider whether the person who developed it could have done a little better job?  Have you ever looked over the crime scene photos and wonder why an item wasn't processed or collected for latent print exploitation?  Have you ever seen half of a latent print on the edge of your lift tape that is unsuitable without the other half, but the rest of the print is nowhere to be seen?  These scenarios and many more are the subject of today's Weekly Detail as we explore the process from crime scene to comparison in search of requirements that must be present in order for a comparison to be conducted and therefore a conclusion to be possible.

Since our discipline is based upon the foundation of biological uniqueness and the permanence of friction ridge skin, it is perhaps most fitting to first acknowledge the source of the impression as having to be present.  Without the presence of the skin source, an authentic latent print cannot be deposited on a surface.  Of course having only the skin with no impression residue would be just as limiting, so matrix is also a necessary factor leading up to a comparison.  Naturally, the source with matrix has to come in contact with a surface, so both touch and a surface are required to result in an impression.  We have to admit there are some other scenarios that don't require matrix or a substrate, such as a flat-bed scan of a finger, or ultra-sound capture of ridges.  However, for the most part touch and a surface hold the latent print impressions we deal with on a daily basis.  The last factor necessary for a comparison to occur is for the environment to be sufficiently non-destructive from the time of deposition until the time of preservation.  The environmental factor is outside the control of even the first responder, but the action of preservation can stop destructive environmental effects.  Before we discuss the importance of actions, let's sum up the first 5 requirements necessary for a correct conclusion to result from a comparison of impressions:

1) Factor 1: Friction Ridge Source was Present
2) Factor 2: Matrix was Present
3) Factor 3: A Surface was Present
4) Factor 4: Touch of the Source/Matrix to the Surface
5) Factor 5: Environment Sufficiently Non-Destructive

Just as there are factors that have to be present for an impression to occur, there are actions within the control of an individual that are necessary in order for a comparison and conclusion to occur.  A smart officer responding to the scene can sometimes recognize very early, even prior to arriving at the scene, that there will be evidence present at the scene that needs to be recognized.  However, some officers may not even realize the need for evidence until well into the investigation.  Take for example routine entry into a residence for questioning that later leads to the discovery that the residence is a crime scene.  The officers likely were not considering the preservation of delicate residue on the door handle as they entered the home.  And even if the need for evidence is recognized, it doesn't necessarily mean that the evidence itself will be noted.  How often have we seen examples of items left uncollected simply because their value wasn't noticed by the investigators who processed the crime scene. 

Once an item is recognized as evidence, it must be adequately preserved for collection.  This is the first point at which efforts can be taken to prevent the destruction of a latent print by the environment.  And the first 3 steps can all happen very quickly.  The same smart officer who realizes on the way to the scene that there will be a need to recognize evidence could literally see the storm clouds over-head, recognize an item in the front yard as evidence, and on the way up to the residence, utilize an object such as an empty bucket to preserve the item for later collection.  That one action prior even to entry into the residence for the initial investigation, could save a valuable latent print identification on a murder weapon that would otherwise be lost to the elements.  This scenario begs the question of how often first responders don't even realize the effects, for example, of sunlight on a dark metal object, or morning dew settling on the recovered stolen vehicle.  How many latent print identifications are lost to environmental effects when the surface could have been preserved?  I propose that we will never know, but we should always strive to adequately train those who are in a position to protect latent prints from the environment during those critical early hours in an investigation.

Of course, the process of collection is just as important, or in some cases much more important than preservation.  A latent print can very easily be destroyed that is on an item not collected properly, not handled correctly, or that is not collected in the right type of container.  Even an officer that has properly collected and packaged an item could fail to preserve the evidence and instead destroy latent prints. How many bags of evidence have been left sitting in the trunk of a dark-colored patrol car on a hot day while an officer has a meal?  Or how often have we seen even our own evidence technicians handling packages without regard to the friction of the packaging material across the items inside?  Even the examiner unpacking the item for development can destroy fragile latent prints.  One of the most obvious elements working against us as we prepare for processing the item for latent prints is time.  How often does our backlog cause items to sit for so long that latent prints evaporate beyond all value.  Again, we may never know how many latent prints are lost to poor preservation of evidence for development.  But through proper training in the latent print process, perhaps we can relate these important concepts to those individuals whom they would benefit the most.

Before we sum up actions which are necessary for correct latent print conclusions, we would be remiss not to include the actions of the latent print technician.  The development technique or series of techniques and their order are all critical in obtaining an impression.  This action alone is the subject of books, but suffice it to say that a necessary action for a correct conclusion is to adequately develop the latent print impression.  Perhaps just as important is the capture of the impression.  The skill and technique of the photographer many times can make the difference in whether the resulting image bears a latent print suitable for retention in the case.  How many times have we wished the lighting were just a little bit different, or that just one more image at a slightly different exposure were taken?  How many latent prints are developed on an item, but overlooked by eager eyes simply traveling too quickly along the surface of an object?  Or even worse, how many technicians see the print, but don't realize its value and simply don't capture it at all!  The action of preserving the impression for examination is critical in the latent process.  So in summary, the next 7 requirements that involve actions are:

6) Action 1: The Need for Evidence is Recognized
7) Action 2: Evidence is Recognized
8) Action 3: Evidence is Preserved for Collection
9) Action 4: Evidence is Collected
10) Action 5: Evidence is Preserved for Development
11) Action 6: Impression is Developed
12) Action 7: Impression is Preserved for Examination

At this point in the process there are two very critical hypothesis and decision points that occur during an analysis of the latent print.  In fact, in some cases these hypotheses may occur prior to the preservation or capture of the impression.  The first hypothesis is that the impression is suitable for retention as evidence in the case.  If a first responder trained to powder and lift prints happens to successfully make it all the way through the first 12 requirements of the process only to incorrectly answer this critical question, then their decision to pitch the lift could literally lead to a good identification going right into the trash.  How many first responders are trained to grade the sufficiency of 3 levels of detail taking into account quality and quantity for individualization?  Yet they are the ones we often task with making this critical analysis decision.  In other scenarios, it is the new examiner who is making this decision in the laboratory as they process an item of evidence.  How many times have lifts been made only for a quick analysis to reveal insufficiency, and the index card hits the trash.  Some of you who work in crime labs with SOP's preventing this may find this practice shocking.  But the equivalent would be simply passing over a latent print as unsuitable during a visual examination and not even attempting a lift or photograph.  A critical decision has been made about suitability for retention of the impression as case evidence, and there is usually no going back on this decision. 

The last decision prior to the comparison phase is whether the impression is suitable to actually compare to another print.  Obviously if the answer is no, you have decided never even to place it side-by-side with another print to even look to see if there is similarity or dissimilarity.  And just as obviously, if you place it side-by-side with another print to look for similarity or dissimilarity, guess what... by your very action, you just determined that the print was in fact suitable for comparison.  How many times have examiners conducted a side-by-side comparison, but then determined the print wasn't even suitable for comparison?  Wait a minute... then what do you call that thing you just did!  You thought there was a chance, so you conducted a comparison.  You didn't arrive at a conclusion.  But that doesn't mean the print suddenly has no value!  I propose that if an examiner places a print next to a print of a suspect for comparison, then that examiner has affirmatively answered the question that the impression was suitable for that purpose, and the print should forever be a part of the case documentation.  And likewise, I propose that only if the examiner knows that no conclusion would be possible, therefore they do not engage in a comparison, is the impression a candidate for being considered of no value for comparison.

There are 4 more actions associated with Analysis that are necessary for a correct conclusion.  First of all, the orientation of the impression must be sufficient.  If a delta is assumed to be a fingerprint but instead was from a palm print, this could result in the impression never being compared and the resulting "exclusion" being incorrect.  Likewise, if the loop was compared in the standard orientation, but it was actually the lower re-curve of the double-loop whorl, even a comparisons to the fingerprint card could result in a missed identification.  Of course another possibility that we regularly encounter involves the incomplete recording of known prints causing the orientation of the detail to be outside the area of capture.  In this scenario we generally have a good idea about the orientation of the latent print and an inconclusive determination is made with the caveat that additional prints are necessary for complete comparisons.

Another action required of the examiner is the recognition and analysis of unique ridge formations.  This may be as obvious as considering ridge endings and bifurcations, but it may be as subtle as recognizing the value of ridge shapes around a scar, the agreement of creases, or the consideration of level 3 detail.  Someone who has never considered these features may find an impression very difficult or impossible to identify compared to an examiner who recognizes and analyses this unique detail. 

Likewise, the recognition of and accounting for distortion is critical in latent print examination.  Some distortions such as the flexibility of skin are easy to work through.  Other types of distortion can throw some examiners completely off the right path.  Examiners who have been in the business for years have probably seen some pretty perplexing things in their own casework.  Over the last decade, dozens of examples of strange distortion have been shared in e-mail newsgroups and web pages on the Internet.  In training, I regularly use an example of a barely-visible scar, one end of which falls right on a feature.  In the healed skin, the ridge next to the feature lined up perfectly with what used to be a ridge ending, and the 1-ridge shift continued all the way down the scar.  Of course on the other end of the scar where an open field used to exist, there now exists a feature.  Some examiners who don't recognize the scar, and only presented with just the immediately surrounding area, will swear up and down that the prints cannot be made by the same source because of the 2 obvious dissimilarities.  What they have accepted as unexplainable is actually distortion, and when presented with the rest of the print they are forced to realize they were too quick to label distortion as dissimilarity.  I propose the same effect may occur in casework when an examiner sees a preponderance of similarity, but cannot get past something that appears different in one area of the print.  Sometimes fault-lines in a twisting deposition or surface striations can cause features that appear reliable, but in fact are products of the distortion.  The balance between distortion and dissimilarity is a delicate one because of the "one dissimilarity doctrine" in our discipline.  However, taking this doctrine to an extreme, and not recognizing and accounting for distortion can lead to missed identifications.

The last topic under the umbrella of Analysis is the choosing and memorization of a distinct group of detail for comparison.  This is done only by looking at the latent print, but if done incorrectly it could cause the "target group" to be overlooked in the known prints.  Pat Wertheim gives an excellent description of this process in his recent Weekly Detail 300 as he related tips for the IAI Certification Test:
 

First, pick your best “target group” in the latent print. A “Target Group” is usually a cluster of three or four “Points” that you can memorize and then recognize again. The “best” target group is not always the most bizarre group or cluster of points, but is a group or cluster of points that you can “anchor” to some other feature in the latent print, like the delta or the core. A single ridge ending that you can precisely measure as three ridges directly above the core is a far better target than some strange configuration of points 15 or 20 ridges away, up kind of near the top somewhere. Chose your “target group” based on how exactly you can tie it to the delta or the core. If there is no clear delta or core, use the “type lines” and find a target group on them. (If you do not understand the concept of “type lines,” it is time to pull out the FBI’s booklet, “Science of Fingerprints,” and study your definitions.) A target group right on the type lines, or a ridge or two above or below the type lines, is much easier to find when you are searching the inked prints that a target group somewhere out in left field.

The whole idea here is to pick your target group based NOT on what is the most unusual thing in the latent print, but rather, what will be the easiest and fastest to find in the inked prints. So, during “analysis,” pick your target carefully – then MEMORIZE it. The best way for most people to memorize a target is to DRAW it. Drawing a target programs it into your brain in the same way plotting the points of a latent print into AFIS programs the computer to find those same points in the inked prints in AFIS. For the test, DRAW your target group of points to force your brain to memorize it better, so you will recognize it again faster when you are searching the inked prints.

Use “Level 1” considerations, as well. If your latent print has thick, wide ridges, don’t waste your time trying to compare it to the inked prints of a person whose ridges are thin and close together. If your latent is about a six count left slope loop, don’t waste time on inked prints much more or less than six ridge counts in left slope loops. Likewise, if the latent whorl has an outer tracing, don’t waste time comparing it to whorls with meet or inner tracings. (If you don’t understand “ridge counts” or “whorl tracings,” get that little FBI “Science of Fingerprints” book back out and study your definitions some more.)

So, ANALYZE the latent print at several levels – find your target group and memorize it by drawing it on a sheet of scratch paper, then look at the pattern for general considerations.


Incorrectly choosing a target group, and not selecting another target group could result in a missed identification.

In summary, there are 6 more requirements in the Analysis phase of the latent process with the first two being hypothesis and decision points and the remaining 4 being critical actions:

ANALYSIS

13) Hypothesis 1: Impression is Suitable for Retention as Case Evidence
14) Hypothesis 2: Impression is Suitable for Comparison
15) Action 8: Impression is Correctly Oriented
16) Action 9: Unique Ridge Formations are Recognized and Analyzed
17) Action 10: Relevant Distortions are Recognized and Accounted For
18) Action 11: A Distinct Target Group is Chosen and Memorized

Next week we will continue looking at additional requirements with a discussion of hypotheses in Comparison and most interestingly, hypothesis sets in the Evaluation phase of ACE-V.  This will lay the foundation for our last article in this series - errors in latent print examination.  If anything in this week's Detail has struck a chord with you, I encourage you to play the tune on the CLPEX.com message board and listen to what other examiners chime back with.  There has been some good discussion on last week's discussion of inconclusive results, and I would like to see the discussion continue on these topics as we forge ahead into next week.

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If you have not yet signed up to receive the Weekly Detail in YOUR e-mail inbox, go ahead and join the list now so you don't miss out!  (To join this free e-mail newsletter, enter your name and e-mail address on the following page: http://www.clpex.com/Subscribe.htm  You will be sent a Confirmation e-mail... just click on the link in that e-mail, or paste it into an Internet Explorer address bar, and you are signed up!)  If you have problems receiving the Detail from a work e-mail address, there have been past issues with department e-mail filters considering the Detail as potential unsolicited e-mail.  Try subscribing from a home e-mail address or contact your IT department to allow e-mails from Topica.  Members may unsubscribe at any time.  If you have difficulties with the sign-up process or have been inadvertently removed from the list, e-mail me personally at kaseywertheim@aol.com and I will try to work things out.

Until next Monday morning, don't work too hard or too little.

Have a GREAT week!