So What Did Margie Say About...

So What Did Margie Say About...

Having gone to many, many gory crime scenes over the last 36 years as a crime scene investigator and bloodstain pattern analyst, I have seen a lot of things.  People say that it takes a "unique" person to deal with the gore. 

 

I have always relied on the idea that physical evidence does not lie, is not prejudiced, and cannot be tainted.  However, as a human being it is often difficult to approach some situations like Joe Friday from the old time Dragnet series - "just the facts" - like a robot.

 

It does take a certain type of person to deal with the physical damages done by crime but there are still psychological issues that are often glossed over.  Crime is obviously difficult for the victim but can be equally as difficult at times for the investigators and detectives.

 

In last night's episode of CSI: Crime Scene Investigation, the victim was released to the father.  The man that in "normal" situations would most likely be the best outcome for the daughter.  Yet, this was a potential disaster.

 

Still, keeping the focus on the evidence: mushrooms in the desert, trace evidence on a shirt, shoe impressions in the dirt, paint flakes from a vehicle accident on the road, etc. emotions were put aside to come to a complete and proper conclusion.  This leads us back to the idea that the evidence will not lie or be prejudiced or even emotional but will lead the investigators to the real truth.  One just needs an open mind, patience, and faith in the physical evidence.  It is there if you look.

Video of full episode is not currently available online but check back at http://www.cbs.com/shows/csi/ 

So What Did Margie Say About...

As a Crime Scene Investigator and Bloodstain Pattern Analyst with over 36 years of experience,  I have a talking point to discuss from last night's episode of CSI: Crime Scene Investigation.  

When the CSI took the photographs of the bloodstains on the tennis court she was in a severe squatting position with the camera held at a steep angle in relation to the stains.  

Take a piece of paper and draw a circle on it.  View this circle from directly above it.  It should look like a true circle.  Now view it at an angle from the side.  Distortion will make it appear to be oval, like an egg.  The more severe the angle, the longer the appearance of the "circle".  Since the ratio between the width and length of a bloodstain is a crucial element in its analysis, this distortion created through the camera angle is troublesome. 

Therefore the photograph should have been taken with the camera directly over the stain - like a birds eye view flying over the scene.  This position of the camera would help to eliminate distortion so that a circle looks like a circle.  A passive drop of blood falling directly downward creates a circular stain but if there is direction (or elongation) to the stain that would indicate motion.  Two very different scenerios in interpretatin to crime scene analysis  

You may say that she was merely taking the photograph to establish the presence and location of the stains on the tennis court.  I would counter that a close up of a dark stain on a gray background looks just like the other dark stains with a gray background and there is nothing to distinguish between the individual stains or anything to significantly establish their position relative to their location on the tennis court rendering this purpose useless.   

One would need to step away and take a photograph with the location of the stain with something fixed and permanent in the background prior to taking the overhead closeup of the stain.  This helps relate the stain location at a later time, usually in court.

 

And then there is the issue of taking a photograph of a fingerprint on a cylindrical clear bottle without a contrasting background or compensating for the curvature of the surface........

In case you missed it View CSI episode