Child to Adult changes in prints

[L.J.Steele]

Can someone put the article in this week's Detail into non-tech terms?

I understand the fundamental concept that fingerprint patterns (Lvl 1?) form in utero and remain unchanged absent certain injuries throughout life. I gather from the summary of the report that Lvl II detail evolves as one ages, and I'm trying to understand the significance of that for matches of juveniles or using exemplars taken when the suspect was a juvenile.

[Pat]

Hi Lisa

I like to talk in analogies. Think of a brand new tire, but imagine that it is the only one ever made from its mold and no other tire has exactly the same tread design. You put this new tire on your car and start to drive. As the tire ages, the tread wears down and it develops little nicks and cuts from debris in the road. Still, you can compare the unique print from when it was brand new to the print as it wears and determine they were both made by the same tire. The tread wears and in some regards it "changes," but you can still identify it as the same.

Think also of a toy balloon with an advertising slogan on it. When it is new and has not been inflated, the printing is tiny. You blow the balloon up and the printing "changes" because it becomes large, but the message printed on it remains the same.

Of course, there is no perfect analogy. Our fingers grow and mature and our friction ridge detail at Level 1, Level 2, and Level 3 all grow larger, similar to the way the printing on the balloon grows larger.

At the same time as we age, the eccrine glands are affected by both biological and environmental factors. Hormonal changes as an adolescent matures affect the chemical make up of the sweat. Later in life past middle age, the eccrine glands quit producing as much sweat and the ridges become flatter and the skin becomes smoother and drier. All the while, we also get little cuts and other damage that results in scars. So the fingerprints "change" for all those reasons. Still, the basic configuration of features at Level 1, Level 2, and Level 3 remain the same and identification is possible.

[Neville]

to continue the mould is actually located below your skin and keeps on reproducing the same detail so those small cuts and wounds will within a month or so be replaced with the original detail however if the wound is deep enough it will effect the mould and therefore remain a permanent scare. I say to people if you have a scare like that you will remember the injury for a very long time. Creases are something else again, thats old age.

[Ernie Hamm]

Pat, your balloon analogy is fine, but the tire tread analogy is not. When a tire ‘wears’, the voids (i.e. friction ridge furrows) which form the tread pattern in association with contact surfaces can DISSAPPEAR in varying stages and locations in the tread during the wear cycle. This does more than ‘change’ the appearance, the wear action permanently eliminates pattern features.

Friction ridge features present at birth will get larger as a person gets older. Patterns and ridges will grow as the individual grows, but the Galton details (aka Level 2) do not change in their formation or in their interval spacing and relative attitude to other Galton details unless there is damage by injury, etc., etc.. Map plots of characteristics made several years (even days) apart can exhibit ‘differences’ for all sorts of reasons and that is why identifications are not made using overlays.

Excuse the dinosaur speak

[Les Bush]

Hello once again Lisa,
Quote from The Detail.
"The project’s goal was to provide the NIJ and scientific community a means for predicting the shape changes of fingerprints during this period of growth in order to significantly enhance the probability of matching an individual’s adolescent/adult fingerprints to fingerprints acquired when the individual was a child."

Your question was what does this mean in non-tech terms?

Firstly the researchers tried to produce a model to predict how the pattern shape of a sample fingerprint would change within a period of growth. The periods of growth selected were between childhood probably <10 through adolescence >10 < 15 years. The quote above includes Adult years presumably >18 years. I havent read the full article so those time periods are assumptions. Based on difficulty getting a diverse sample population the researchers look like they settled for a group within the >10 but < 15 years and collected fingerprints of patterns over a 3 year period. They then conducted research on these and found that a model for predicting pattern changes due to growth was not possible. The second part of their study was to confirm that fingerprint patterns taken from each donor were identifiable and this was confirmed.

In the grown up world of crime we do find examples of young offenders being recorded and who subsequently continue with a life of criminal activity. The trend for this may becoming more prevalent as crime gangs recruit younger members as a means of minimising periods of detention, or avoiding detention altogether. The youngest child I have identified on the trigger of a rifle was 10 years old and that was in the early 1990's.

The principles of fingeprint identification science are based upon the permanent & unique patterns of detail (1, 2 & 3) formed during foetal life in the second trimester of gestation. The anatomy and physiology of this special skin remains constant throughout life until death. Simply examining the effect of adolescent growth on the changing size of the pattern area is very much like Pats analogy of putting more air into the balloon. Cheers from oz. Les

[L.J.Steele]

Just to make sure I understand this in non-tech terms.

Assume I were to create an excellent quality examplar 10 print of my child at, let's say age 1.

At age 10, her fingers will be much larger.

At age 20, larger still (and likely at full growth).

Assume no scaring or other abnormal changes.

I understand that all the 1st lvl (general pattern) detail will be the same over those 20 years.
Despite the growth all the 2nd level (ridges and bifurcations) detail at age 20 will have been there at age 1, just much, much more densely packed?

Ditto all the 3rd level detail (ridge shapes, pores, etc.)

So as one grows, the ridges don't, say, get longer and add more ridge details and pores too them, the spacing just gets wider?

(That's what I always understood the theory to be, just want to make sure that I understand it correctly.)

[Neville]

Hi Lisa

Yes I think you have it one.

All this was researched originally about 100 years or more ago; it has been repeated by various people since. I imagine in every fingerprint office of any size there will have been someone who has done this with their children. I remember being told of two or three experts in New Zealand who have done this, one expert used identical twins (a double dip) not sure if they were his twins though.

Matching a senior citizen's fingerprints taken at the mortuary with those taken when the person was a juvenile is a very normal process that requires no special skill.