CLPEX Chat Board

Here's an article I ran across from a different forensics forum. It's interesting with respect to making a delineation between permanence and persistence that I don't think people in the discipline would acknowledge.

Permanence is the unchanging presence and appearance of friction ridge arrangements and their attributes between recurring observations of the skin. Permanence was evaluated from direct photographs of fingers collected over a period of 30–45 days (covering one or more skin regeneration cycles) as well as after 8 or more years had elapsed. Persistence embodies the operational concept of whether or not a pair of images displays
sufficient similarity upon which to base an informed decision that they were made by the same finger, while acknowledging certain dissimilarities or distortions due to friction ridge physiology, image capture, matrix, substrate, and applied pressure.

It seems as their definition of persistence is basically that of a conclusion or arguably what SWGFAST referred to as:

The Scientific Working Group on Friction Ridge Analysis, Study, and Technology (SWGFAST), a recognized body charged with formulating guidelines for the friction ridge impression examiners’ discipline, posits that forensic friction ridge impression examination “is an applied science based upon the foundation of biological uniqueness, permanence, and empirical validation through observation”

So if, I'm reading this correctly, persistence has shifted from a function of the skin to the transfer of the impression from the skin to an object. Furthermore, it is basically wrapped up in the notion of sufficiency and part of an examination. I've really only known it to be or heard persistence used in the context of the fact that the arrangement of ridges maintain their sequence, direction, form and spatial relationship, as part of a biological process (skin cell formation and sloughing) over time. Or in English, fingerprints don't change over time unless you damage the skin.

Thoughts?

Link to paper

With utmost respect for the authors of the paper, some of whom were serving on SWGFAST when we shifted from referring to friction ridge skin as "persistent" rather than "permanent," I recall our SWGFAST discussion of the terms as related to the skin itself, not prints or impressions therefrom.

"Permanent" could be interpreted as meaning, in effect, that friction ridge skin NEVER changes from birth to death. But we know that both the skin and impressions may change through scarring and aging. Therefore, SWGFAST agreed that "persistent" was a better term for the skin because conceptually, scarring and aging could be accounted for without contradiction or exception. As I recall the discussions in SWGFAST, the terms were discussed only in relation to the skin itself. I do not recall any distinction ever being suggested in use of one term to apply to the skin, the other to a print or impression.

That said, I can understand that for the purposes of this paper, a finer distinction is drawn between the skin itself and prints from the skin. To my mind, for normal applications such as routine discussions in the lab or testimony in court, this would be a somewhat pedantic and confusing distinction.

But I do not see a conflict between defining the terms more precisely for purposes of the paper, and the more general use of the term persistent to describe friction ridge skin formations in daily discussions and testimony.