UPDATES ON CLPEX.com

Updated the Fingerprint Interest Group (FIG) page with FIG #44.  Visit the CLPEX.com FIG page to see this example of  a ridge disruption above the core, submitted by Sandy Siegel.  You can send your example of unique distortion to Charlie Parker: Charles.Parker@ci.austin.tx.us

Inserted Michelle Triplett's Keeping Examiners Prepared for Testimony (KEPT) #19: Other - Scientific Basis for Individualization.   Discuss this topic on CLPEX.com - a discussion has been created for KEPT.

Updated the Detail Archives
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we looked at the CBS Sunday Morning special on fingerprints.

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Superglue Oddities
by Charlie Parker

The Case of Black Ridges and Not White!

This case occurred in the early 80’s when superglue fuming first started. The case was a Kidnapping and Sexual Assault. The victim had been taken from a local Stop and Rob and forced to a motel when the victim was assaulted. As the suspect was leaving he tossed the room key on a table. The key was the older type with a large black triangle key fob that you used to see motel keys on (if anyone can remember that far back). We had just obtained our first aquarium (cracked that would not hold water and someone did not want anymore), and had actually fumed another piece of evidence in a drug case a few days earlier. So this was my second case involving superglue fuming. When the key fob was removed latent prints could be easily seen. It was photographed with a 4X5 Graflex camera using Technical Pan Film but the pictures were strange. When a suspect was developed the comparison was started it was determined quickly that we were comparing black ridges with black ridges and not the expected white. Upon looking at the key fob it had a coat of material on it and when the subject touched it the material was removed. It was a classic take away print with the glue reacting to the surface of the plastic and with the black underneath we had ridge detail black with white furrows.

The Case of Fuzzy but Reversed

A few years later we were packing drug evidence into glue tanks and gluing everything in sight. We begin to notice that some of the prints were looking a little fuzzy and when we observed those fuzzy prints we could generally find the mirror image on some other item. Soon we learned about lateral transferred latent prints and learned quickly not to pack items so close together in the glue tanks. Lateral reverses do occur and has been documented in several articles over the years.

The Case of Sharp but Reversed

A few years ago when teaching a class on Techniques of Developing Latent Prints I had a student approached me and ask why did the Superglue develop latent prints on both sides of the plastic. I said because you touched both sides and he denies that he did. I then said you got it too close to someone else’s and it was a lateral transfer. He said there was not anything else close to it and the print on the other side was EXACTLY OPPOSITE and a REVERSAL of each other. I said “yea right” and asked to see it. He produced it and sure enough it is the exact same print exactly opposite sides of the small piece of plastic. The plastic is gray and very thin, probably about 2 mil where you can shine light though it. I call it the reversal by osmosis. I have yet to reproduce this phenomenon.

The Case of the Slipping Ridges

This is not my case but was sent to me. A piece of aluminum foil was processed with superglue and then the prints on the foil were treated with Rhodium 6G and several ridges on each latent print just slipped away from the surface. You can see them as they are like pieces of spaghetti hanging down from the prints and the ridges are intact but just not part of the latent anymore. I have shown this one to a number of people and 3 have told me that they have had a similar occurrence with Rhodium 6G.


The Case of Superglue Trees

This is not my case but I was made aware of it. Apparently some items were processed with superglue and the glue polymerized out from the surface into what I would call a number of small stalks with branches on the end. It looks like a little forest growing out of the surface of the item. This has been attributed to either static electricity or spore growth. I have not had this occurred in any of my processing and only saw the picture of it recently. Pretty but weird.

Perhaps you have an unusual CAE (Superglue) Story you would like to share.

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KEPT - Keeping Examiners Prepared for Testimony - #19
Other - Scientific Basis for Individualization
by Michele Triplett, King County Sheriff's Office

Disclaimer:  The intent of this is to provide thought provoking discussion.  No claims of accuracy exist. 

Question – Scientific Basis:

How do you know that fingerprints are unique and permanent?

Possible Answers:

a)      The FBI has been keeping records since the early 1900’s and no two fingerprints have ever found to be the same.  There are also hundreds of thousands of records showing that fingerprints of individuals remain the same.

b)      Several statistical studies have been done to show the possibility of duplication is virtually impossible.

c)      By looking at how the ridge configurations are initially formed. Generally speaking, the interpretation of ridge configurations can be grouped into two categories. The first considers ridge configurations or patterns to be “primary foci of evolution” and therefore directly determined by genetic factors. The second interpretation, proposed by Cummins in 1926, considers ridge configuration as a product of epigenetic processes involving response to growth forces. This second interpretation suggests that ridge configuration is not directly determined by genes but rather is indirectly determined by adjacent tissues with which the developing glandular folds of the basal epidermal layer interact. These adjacent interactive tissues may include the volar skin itself, the soft tissue of the dermis, bone, and/or other epidermal appendages like the fingernails.

d)     Several researchers have done embryonic studies of friction ridge growth and it’s been determined that friction skin patterns are formed by pressures present during the growth process.  Since it’s impossible to duplicate the pressures on any finger or any person, no two fingerprints will ever be the same.  The friction ridges stop forming during a certain time during fetal growth.  Once the growth process stops the friction ridge arrangement is persistent until death and decomposition.

Discussion:

Answer a:  Although this answer is a correct statement, this is empirical evidence.  It shows what we’ve seen to be true but it doesn’t tell us why this event happens (it supports the scientific law but doesn’t give enough data to establish a scientific theory).

Answer b:  The statistical studies done also support uniqueness but they don’t show why it’s impossible for fingerprint arrangements to ever be duplicated.

Answer c:  It’s important to use explanations your audience can understand.  This answer may be adequate for those in our discipline but it may be too much for a jury (an explanation quoted by W. Babler).  Once jurors tune out what you’re saying, it may be very difficult to ever get them back. Be careful not to talk above the jurors level and be careful not to make something so simple that it appears that you’re talking down to them.

Answer d:  This answer doesn’t mention the particulars of the friction ridge growth process but it does give accurate information that’s easy for a jury to understand.  Answers a and b support the scientific theories established by research scientists but this answers states the research done to establish the scientific theories.

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