CLPEX Chat Board

For quite a while I’ve been emailing with several people about different visual clues in prints and what these clues tell us. I think we’ve finally got it written in a form that’s ready for some review. Since I haven’t gotten my normal Monday morning Detail, it seems like a perfect time to post this.

Does anyone see any glaring problems with these definitions? Any subtle problems? Anything that could be worded differently or needs additional information? Is this how others use these visual clues? Are people using other words to describe these clues? Are there other visual clues that can be added?

Any feedback is appreciated!

Red Flags (visual abnormalities which serve as warning signs)
-Line of absence or shadowing (indicates double tap or slip)
-Fault line or shadowing (moon shape indicates slip or double tap; v-shape indicates slip or twist)
-Multiple vvvvv’s or stacked bifurcations (indicates smearing, double tap, or twist)
-Ridges not running in concert, sudden directional change in ridge flow (indicates double impression, where the two prints meet)
-Misaligned ridges (indicates double impression, smearing or scar)
-Artifacts off ridges, marks in furrows, or ridges being dragged into the furrows (indicates twisting or slippage)
-Ridges crossing, superimposed, overlapping, or checkering (indicates double impression)
-Wave or hump in ridges (indicates scarring or movement during live scanned usage)
-Ridge breaks (could indicate temporary or permanent scarring)
-Ridge breaks with puckering (indicates scar)
-Ridge breaks with ridges being pushed apart (indicates wart)
-Extra thick ridges and narrow furrows, a form or compression (indicates deposition or direct pressure)
-Ridges gathered at one side, a form of compression (indicates lateral or longitudinal pressure - ridges gather in the opposite direction of movement)
-Ridges gathered at one side and moon shape fault line or lines of smearing, a form of compression (indicates twisting – movement is in opposite direction of compressed ridges - ridges close together on right indicates counter clockwise twist.)
-Lines running or streaking through area of touch and outside the area of touch (indicates substrate interference)
-Lines running or streaking within an image and from an image, a dark area or smear may be accompanying the streaks (indicates movement during contact between the friction ridge skin and the substrate). The lines are running parallel to the direction of movement. The direction of movement may be established by the compression of ridges.
-White smear (indicates smearing of latent after processing)
-V in the top of impression on the edge (indicates double tap)
-Darker areas (indicates pressure or excess moisture)

Compression
Ridges gathered closer together than normal. The result of pressure applied to the friction ridge skin during contact with the substrate. Compression could be due to the flexibility of the friction ridges or the flexibility of the substrate. Compression can change the appearance of an image (size, shape, thickness of ridges, color of ridges) but not the friction ridge characteristics.
a) Latitudinal movement: direction of pressure is in the opposite direction of compression (if ridges are compressed close together on the bottom then the movement is upward).
b) Longitudinal movement: direction of the pressure is in the opposite direction of compression (if ridges are compressed close together on right then the movement is to the left).
c) Twisting: Ridges gather closer together on the opposite side of motion (ridges close together on right indicates counter clockwise twist)
d) Direct pressure: ridges get thicker, furrows get narrower

Double Impression
A double impression can refer to either overlapping prints (overlays) or double taps.

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 flow. Double taps are made in close time proximity to the first friction ridge impression. Double Taps are made by the same finger.

Overlay
A double impression where additional friction ridges overlap an existing friction ridge image. Overlays will not coincide with ridge flow and may exhibit some type of checkering. Overlays are not immediate double impressions of ridge detail. Overlays may or may not be the same finger impression or made by the same person.

An impressive list, Michele! I can't think of anything that you've missed.

Somewhere (!) I have some notes taken at a training session on the examination of latents that discusses "red flags". I've just gone through my desk and filing cabinet here at the office without finding it. I'll check at home tonight. If there are any that you don't have listed (which I doubt), I'll get back to you.

Michelle,
I would only caution that some characteristics of distortion are not necessarily 'red flag' items. TAS

Terry,

Can you explain this more in detail? I realize that red flags don’t always indicate distortion has occurred, they are visual observations that indicate that distortion ‘may have’ occurred. What kind of characteristics of distortion wouldn’t be considered red flags?

Here’s 2 more I’m adding to the list:
-Background around the image is dark (indicates the ridges are white)
-Dots in the furrows (the matrix may have adhered to the background and not the latent, indicates a color reversal)

Why is there a need to differentiate between overlays and double taps? I could see an issue arising with calling something a "double tap" and being questioned on how we could indicate that there was a close time proximity between the two impressions. It would be easy to start speculating about the time intervals between the impressions.

When I am analyzing overlaid(?) impressions I try to use the impressions independant of each other. It doesn't matter if they are the same finger in close time proximity or not, they have to stand on their own.

Good point. I agree that it’s important not to overstate the knowledge we have and stating something is a double tap can’t really be established. I think a valid argument on the other side of this discussion is that this term is commonly used in our discipline and we need to articulate what is meant by it. I’ll work on rewording this.

Can you explain this more in detail? I realize that red flags don’t always indicate distortion has occurred, they are visual observations that indicate that distortion ‘may have’ occurred.

Michelle, I guess I am suggesting that some of your listed items are normal distortion 'realities' that we cope with daily ( like the extra wide ridges of heavy dep-pressure , as an example) and that the term >Red Flag< need not apply to all of these. In my mind, the term 'red flag' should reserved for the more uncommon things ( the multiple vvvvv's , the angular ridges etc.) which when I observe them, I say to myself, "that's something MORE than 'normal' distortion".

That's all.

Perhaps a common terminology and definitions to train new latent print examiners.

Perhaps a common terminology and definitions so latent print examiners from different areas have a common language that is understood.

Double-Taps does not mean the same thing to all examiners.

Terry,

Ok, I understand what you're saying. Saying that these visual signs "could indicate" a certain type of distortion would be better than stating that these visual signs "indicate" that distortion has occured. I'll change that on each line.

Thanks!

In my mind, the term "red flag" indicates only that something is going on that I should take note of. It doesn't necessarily mean that there is, or is not, distortion, only that there is something of note that I should be aware of. I would figure out later in my analysis if that "something" is distortion -- to me, the red flag is just a mental note to look into it further.

I thought this was a great thread that died too young although looking at it again with 14 responses and over a 1,000 hits maybe it did not.

Like Michele I am interested in Distortion Effects. The difference I think is that she is working to incorporate them into red flags that would be associated with complex latent prints. My desire is to look at all effects of distortion that occur from the most simple of latent prints to those that are complex. Most writers have said that distortion effects are in most if not all latent prints, however most do not hamper or influence the Latent Print Analysis or Individulization. But when they do, they can do so in a very major way.

Some of my associates have told me that "distortion is distortion and why complicate something if it has no negative effect on the indentification".

IMHO by studying those found in the most simple form, it will help us to understand those in the complex form. I also think that this is a topic that has a lot of potential and interest. Alice's class in San Diego about distorition has sold out. To me this indicates a wide interest in the topic that we are only scratching.

Hopefully there will be additional studies by Alice, Michele, g, and others to add to the collective knowledge.

I ask those that are reading this to comment on Michele's terms and definitions. Add your own to this post with definitions or even if you think that the descriptions of distortion effects are wrong. Only by open discussion can this sometimes very important aspect of distortion be fully explored and refined.

Add the issue of fingerprint artifacts to the list. Particularly those artifacts created by Live Scan devices where the Live Scan cleans up the image to remove the smudge and distortion needed to explain the artifact.

Shane

Charles,

I haven’t given up on this, in fact I’ve driven my co-workers crazy with it. And I’m not only concerned with complex prints but all visual clues and what they suggest to us. I think when I say, “hey, you wanna see something interesting…”, all my co-workers know I’m probably talking about something other than the ridge detail. Even something as simple as air bubbles produced while lifting the latent now catch my attention. I started out calling these ‘Red Flags’, then changed it to ‘Yellow Flags’ because red flags seems to indicate that these visual clues hampered the identification process. Now I’m thinking that ‘visual clues’ is an even better description…… but who knows.

With each example I find, I end up having to alter the description a little bit, but that’s a good thing because the descriptions are becoming clearer all the time.

The problem I’m having is that keeping these examples at a reasonable size isn’t easy for emails. I think I’m going to have to start saving them in a different format. I never imagined that I’d want to keep so many examples.

This has been more useful than really thought it would be. One of my coworkers was asked to determine if an image was left on a window through a screen or after the screen had been removed. The example we were collecting made it easy for her to verbally describe why she came to the conclusion she arrived at.

I have a few examples of livescan artifacts. But if you have any fun examples, I’d love for you to send them to me.

michele.triplett@metrokc.gov