Topic: Toolmarks and Handedness

[KLRogers]

Hi, im in my final year of a forensic science degree and my project is on whether you can tell if the person using the tool was left or right handed but i can't find any previous research on this can anyone point me in the right directions?!

Im also struggling to find anything on horizontal angles of tools etc...

Any help would be great!
Thank you

Kirsty

[Dom Denio]

Ms. Rogers,

I am not aware of any forensic research that has been conducted in this area. Additionally, I am not sure of the value that this type of determination to an investigation or case at trial. This may be why you are having difficulty.

Best of luck with your studies,

[Angel Moses]

I can't think of anything that a Firearms/Toolmark Examiner might look at and be able to distinguish personal attributes about the user of the tool.  Because what we look at has really no personal motivation or signature besides the mechanical signature transfered from one item to the other. 

Personal attributes such as height and even handedness maybe useful and determined when looking at or evaluating a crime scene.  By this, I refer to line of sight or trajectory of projectiles due to intervening objects (height); or to limitations of movement due to space confinement or placement within an area (handedness).  Without information about a specific crime scene, you can't infer such things about a person based on physical evidence alone.

I'm not clear as to what you are looking for as far as "horizontal angles of tools".

[hjeppe]

Kirsty
I have heard this issue debated as theoretical concept on numerous occasions and certainly believe attempts at validation must have been made over time. Unfortunately I have to say that the most active theorizing on this issue, seems to come from more inexperienced/ trainee examiners. I have yet to find valid published research on this theme. I believe the biggest issue is the problem of legitimacy. It's sort of similar to Nostradamus' predictions; It makes perfect sense and is often spot on; after the fact. This does not help us too much in practice. I do not mean to sound haughty at all, you certainly have a valid question, it might just not be too easy to formulate a valid research hypothesis. If you do continue with this project, I would suggest you start by narrowing down your focus from "tools" to a specific class of tools. E.g.: I cannot logically see how handedness could be deduced from the markings resulting from application of a tool such as a punch or a bolt cutter. A chisel, on the other hand, might hold some promise as logic would hold that the "action" of the tool should "angle away" from the applied force (under perfect conditions). In practice, however, circumstances are hardly ever perfect. The application of a tool is most often determined not by the preference of the user, but by the force of necessity (e.g. if the obstruction to be removed is situated at an angle so as to force the application of a tool in some or other direction). Thus, and certainly my experience supports this, a left-handed person will often manipulate a tool with the right hand, simply because the specific situation demands it.
Since there has been no (to my knowledge) previous published research on this subject, it might seem like a very interesting concept, but in all fairness the "bottom line" on this topic always seems to be a question of dubious practical applicability. However, any research, if properly done, is of value to a discipline even if it sometimes raises some questions (and eyebrows). This is not intended to discourage you in any way, but your topic, if evaluated with an experienced practical approach, is very complicated with almost incalculable variables. Sometimes it takes quite a while for us to know enough to know how much we do not know. That said, good luck with your research and don't be discouraged by seemingly negative feedback. If you are thinking of continuing in this discipline, you might as well get used to it.

Regards
Harry Jeppe