What's in a skidmark?

So every now and then myself and a couple other smart ass types here get on an email subject that we just can't kill. This particular day, we were discussing skidmarks. Here's the email that started this conversation.

Sent: October 6, 2005


Reply 1 from SmartAss 1: Sent October 17, 2006
Skidmark Alert: Numerous micro-skids were located at 10:23A on October 17 in the downstairs bathroom by the back entrance. I was not able to identify the author, despite the unusual dispersal pattern of the micro-skid distribution. Using the color analysis swatches from my handy SIK (skidmark investigation kit), I determined the samples fell somewhere between PANTONE 19-1020 Dark Earth and PANTONE 17-1134 Brown Sugar. My color-blindness interferes with an accurate assessment, but I did the best I could. I did make the appropriate notations in my skidmark log. I’m issuing this formal BOL (be on lookout) notification for the culprit.

Reply 2 from SmartAss 1: Sent 10 minutes after Reply 1:
Skidmark Investigation Update:
Following the instructions in my skidmark field guide, I have completed the initial ballistics testing and physical analysis. First, I attempted to classify the missing pellet using evidence available from the impromptu “pro tempore” skidmark analysis. Lacking sufficient evidence to quantify shape and taper, I will loosely classify this pellet as “elliptical or oblong”. I can not rule out the very real possibility that we are dealing with an E unum pluribus (out of one, many) scenario involving multiple pellets. I have concluded that the pellet(s) in question contained mostly dark pigments, the color was mottled, and since the skidmarks themselves were so narrow, I infer that the firmness of the projectile(s) was not loose, and would be more appropriately classified at the “solid” end of the scale.

Since we are operating with imperfect and incomplete information, I was forced to move directly to more sophisticated assessment techniques. My initial objective was to uncover any “low hanging fruit” as it were, that might help to limit the scope of the investigation. I was hoping to get lucky and make a “falsus in uno, falsus in omnibus” claim (false in one, false in all), but the limited evidence did not support this effort.

Next, I searched for any unusual class characteristic parameters that might illustrate a potential mismatch between pellet and bore indicating the pellet was launched manually or by a third party. I have assumed for the time being, we are dealing with a standard delivery vehicle and bore, and will ignore non-standard (smooth bore) tests for the time being. Lacking any evidence of forced exit, I will also stipulate this pellet was induced naturally without physical or pharmaceutical assistance. In an attempt to identify evidence of unique land and groove marks in the “barrel”, I examined the skidmark patterns for any correlation to pellets launched from known striated and non-striated bores with no success. Analysis of the skidmark pattern also rules out the chance this was let loose by an abnormally undersized barrel. The possibility of release from an unusually oversized bore remains a distinct possibility. If I can find the time, I’ll look for evidence of any deceptive striations or unusual chamber marks.

I’m also going to recommend increased surveillance in case we’re dealing with a serial marker. We like to refer to multiple offenders as “taggers”, and increased surveillance greatly magnifies the chances of us catching the offender flagrante delicto (red-handed).

Response to Reply 2 from SmartAss 2:
Measurement of the macro-hardness of materials is a quick and simple method of obtaining mechanical property data for the bulk material from a small sample. It is also widely used for the quality control of surface treatments processes. However, when concerned with coatings and surface properties of importance to friction and wear processes for instance, the macro-indentation depth would be too large relative to the surface-scale features.




The End! Welcome to my world!