Distortion Question

[Charles Parker]

In the article “The One-Dissimilarity Doctrine in Fingerprint Identification” by then Assistant Professor John I. Thornton (I think he has his Doctorate now) that was published in 1977 on page 3 of his article (or 91 as it came from the Journal) he talks about an aspect of distortion he calls “chattered”. The full quotation goes like this “The general nature of the latent impression does not suggest that the finger registered imprecisely due to debris on the finger, nor does an examination of this impression reveal any clear indication that the finger “chattered” over the surface upon which it was developed, thereby creating an additional ridge.”

I am familiar with the term “chattered” in vehicle accident investigation, but I am interested in more description or explanation of the term. Better yet if someone had an example of a “chattered” distortion that they would be willing to share.

I am also interested in how other examiners may use the term “overlay” and “double tap”. Are “overlay” and “double tap” just two different words for the same type of event? Or is there separate meaning such as:

Overlay---a double impression where additional friction ridges overlap an existing friction ridge image. Overlays will not coincide with ridge flow and will exhibit some type of checkering. Overlays are not immediate double impressions of ridge detail.

Double Tap---a subtle double impression where additional friction ridges will coincide or be close to running in the same direction as the existing ridge of flow. Double taps are made in close time proximity to the first friction ridge impression.

OR any other description, definition, or usage that you may have of the terms “Overlay” or “Double Tap”.

I have a problem with the time thing and I am interested in how other examiners may use or define these terms.

If you cannot answer this posting, you can e-mail me your response.