So What Did Margie Say About...CSI: Code Blue Plate Special

The first blog entry reference the repeat episode of CSI: Crime Scene Investigation titled "Code Blue Plate Special" appeared on 5/30/13.

 

Tonight I'll focus on the bloodstain pattern analysis.  I say bloodstain pattern analysis instead of blood-spatter because there is more to the science than the 'spatter'. 

 

In bloodstain patterns there are stains that are created through 'active' events and stains that are created through 'passive' events.

 

In this episode the significant analysis of the blood was done on passive stain patterns.  When the blood flows it will always flow downward due to gravitational pull.  When you look at the downward flow on the chin of a deceased you know that their original position was upright when blood began to flow.  Gravity pulls it down.

 

The same is true when looking at the flow on the clothing.  If a person is upright when they suffer a blood letting injury and maintain that position then gravity will pull the blood flow downward and this will be demonstrated on the staining on their clothing.  If they are on the ground when the blood flows then gravity pulls it downward across the curves of the body and this staining is evident on their clothing.

 

Where blood pools and where it saturates the clothing are also telltale indicators of body positions and subsequent motion or movement.

 

So you see, you don't have to have spatter, gunshot impact spatter or otherwise, to be able to interpret the language of blood and hear the story that it has to tell.  Even in the midst of "action" such as eight people being shot, the quieter evidence was the most informational.

So What Does Margie Say About....NCIS: Shiva

The repeat NCIS episode on 8/20/13 titled "Shiva" clearly demonstrates why any investigator or supervisor too close to the crime should not be involved in any capacity with the investigation. 

 

Oftentimes the agency itself is eliminated from being the lead agency in the investigation.  In the Commonwealth of Virginia, a crime involving someone related to or part of a local law enforcement agency is usually handled by the Virginia State Police.

 

Even if the local agency investigator could remove his emotions from the circumstances, which is almost humanly impossible, the "smell test" won't be passed at court time.  Any defense attorney will go full tilt to show the jury how prejudiced and emotional the investigator is due to the ties to the victim.  The tie may be a direct relationship or just the result of working in the same agency as someone related to the victim.

 

Any investigator needs to keep an open mind and a level emotion.  I dare say that anyone with human empathy and compassion could not do this if the situation is just too close to home.

 

An overzealous investigator or supervisor is a detriment to a good outcome regardless of how pure the intentions are.

 

It is never a bad thing to ask for assistance, especially when the result is the ultimate truth.

So What Did Margie Say About...CSI's Sexual Assault Kit

The 8/14/13 repeat episode of CSI: Crime Scene Investigation titled "Backfire" had its first blog entry on 4/11/13.

 

This time I'd like to talk about the Sexual Assault Kit that turned the investigation in this episode.  I haven't spoken of the contents of the kit prior to now.

 

The clothes are taken.  If not all of the clothes, the underwear in particular is taken at the very least.  The victim may be asked to remove her clothing while standing on a large sheet of paper so that any trace evidence that falls off during the disrobing may be collected and possibly used to help identify a perpetrator.

 

The fingernails are scraped, again to collect any possible trace or potential DNA from the suspect.

 

Wounds and injuries are photographed.

 

Swabs are taken and potential evidential fluids are obtained from the mouth, the anus, and the vaginal area.  Sometimes the inner thighs are swabbed as well. 

 

If the interview of the victim suggests that other areas are to be swabbed, then that area is swabbed as well.  For instance, the suspect may have kissed or licked the victim.  These areas need to be swabbed.  The suspect may have bitten the victim  These areas need to be swabbed and photographed and if bite marks are present, casts need to be taken.  And obviously, if the victim ejaculated on the victim or other object, these areas need attention. 

 

Hair samples used to be taken in the form of combings of the pubic region in case suspect hairs were present.  As I have mentioned in the past, microscopic examination of hairs is no longer routine and hairs that naturally fall out will not have the root present to get a DNA profile.  But if hairs from the suspect are pulled out - now there is the potential to have the root present and possibly a DNA profile from the suspect.

 

Times have changed over the last few decades and sexual assault victims are interviewed and treated differently than in the 'good ole days' when it was essentially up to the victim to prove that she didn't entice the perpetrator and wasn't just crying 'wolf'.  In the 70's and 80's the rape victim had to essentially have suffered severe injuries to obtain any credibility to her accusation of assault.

 

Thank goodness we are past that.  Unless, I guess, you are a drunk teenage girl who has overdone the beverage intake at a party attended by high school athletes.  But this is a topic for another day.

So What Did Margie Say About...Systematic Approach to Crime Scene Investigation

Hello faithful followers and newbies as well.  I wasn't home last night so I thought I'd discuss a bit about the systematic approach to crime scene investigation.

It actually begins way before you get the call.  You must check your vehicle to make sure that it is functional and completely stocked.  How is your oil?  Does the vehicle have a full tank of gas?  How is your supply of bags, markers, tweezers, gloves, etc?  Is your camera functional?  Do you have spare batteries and memory cards?

When you get the call then you begin an emotional transformation.  You need to handle your emotions while doing your job.  A horrendous scene, especially one involving a child, takes a toll on you but it cannot interfere with the duties required of you.  A mental preparation and calming is essential.

Then you do a preliminary walk through.  The first priority on any scene is safety.  Safety and care of the victims and the law enforcement personnel.  Once the scene has been declared safe and medical attention has been rendered to those victims that can be helped by that, then comes the evidence.  One must evaluate the environmental conditions and establish a priority of the evidence to be gathered.  For instance, if you are working an outside scene and it is raining or soon going to be raining you must take precautions to protect vulnerable evidence from the environment.  A heavily traveled area is also a priority.  But you must determine the scope of the scene and the potential evidence prior to beginning any collection.

Once you know what you are dealing with and have an idea of the tools you will need to deal with what you have, then you begin documentation and collection.  Documentation consists of notes, photographs, and sketches.  You should takes notes on EVERYTHING.  What do you see, hear, smell, feel, and observe?  Are the lights on or off, what is the temperature, what is the thermostat setting, is anything out of place, and on and on.  Then you photograph to place the item of evidence in a relationship within the scene and then a close up of the evidence itself.  If it is in a difficult location such as under something or stuck in something or on top of something then supplemental photographs may be necessary.  Then the item is measured for placement in a sketch.

Then you collect and package for the best possible preservation of that piece of evidence.  Labeling is important as well.  You should have already designated areas for evidence, equipment, and trash.  Everything has a place and should be put in its place.  That is easier for organization and accountability.

At the final phase you ask for a 'fresh pair of eyes' if possible to review the area and view the scene to see if they notice anything that you may have overlooked.  This is also the time to dust for fingerprints and leave that black powder on everything.

Once back at the office or the laboratory is when the real fun begins:  PAPERWORK!!    

This is really just a brief discussion and "the tip of the Iceberg" but it gives the basics so that any Titanic disaster should be avoided.

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So What Did Margie Say About...CSI: Dead of the Class

The repeat CSI: Crime Scene Investigation episode titled "Dead of the Class" airing on 8/7/13 also had a post from 3/21/13.

 

The episode begins with the description of the deceased females neck wound as an irregular laceration.  Wound interpretation can lend itself to some valuable information in a criminal investigation.

 

First there is a distinction between a cut and a laceration.  A laceration is not a defined wound but more of a tear.  A cut is a wound which has been 'sliced' and displays clean edges.  Also a cut is longer than it is deep and a stabbing is deeper than it is wide.

 

A wound's edge can often give information as to the width of a blade, if the knife has a hilt, if the blade is single or double edge, and if the blade is serrated. 

 

The depth of the wound may give an indication of the length of a knife's blade.  One must be cautious because if strength and force is applied during a stabbing the knife can go into the body farther than the length.  The skin has elastic properties and may reconstitute to an original state once the knife has been withdrawn.

 

I have spoken of Langer's Lines before.  These lines which are also referred to as cleavage lines is used to describe or define the direction within the human body along which the skin has the least flexibility.  One must also consider if the wound is located in a fleshy or fatty portion of the body or in an area where bone is prevalent.

 

Retrieving information from a wound, and documenting these informational points, is a good investigative tool.

 

Of course, nothing will ever be as definitive as "the Mark of Zorro".  Crime scene investigators should be so fortunate.

So What Did Margie Say About...NCIS: Devil's Trifecta

The repeat NCIS episode on 8/6/13 titled "Devil's Trifecta" begins with FBI agent Fornell getting shot and then shooting through the front windshield of a vehicle.

 

Bullet holes in the windshield glass are capable of providing information as to the sequence of the shots from the radial cracks generated by the damage.  Radial cracks will not cross an existing radial crack so it's easy to track the crack and see which was the original and which cracks then stop the others in their path.

 

Bullet holes in the windshield glass are also capable of providing information as to which direction the bullet was traveling when the damage was created.  A crater is created which shows direction as well as the side view of the glass gives you distinctive radial cracking.  'Radial cracks create right angles to the rear' due to the pressure and strain on the glass when the damage is created.

 

All is well and good so far but what they didn't account for is the potential for ricochet bullets once they hit the windshield.  The slope of the windshield also may create a problem with firing your weapon into and through the glass.  There have been cases of officers attempting to shoot through the windshield and end up injuring themselves by their own bullet ricochets.

 

Also it was a good thing that the bullet that hit Fornell actually hit the bullet proof vest.  Why didn't the shooter go directly for the head shot?  With a driver in a vehicle it would seem that the most visible and largest target would be the head of the driver.

 

Many years ago manufacturers designed a safety glass which is supposed to break into cubes when broken and damaged.  In a scene situation, it is good to consider how to protect the glass from 'shattering' when it is moved or towed for processing.  One good bump and all that great information is just a pile of cubes in the front seat and floorboard of the vehicle.  

The 7/31/13 "Last Woman Standing" episode of CSI: Crime Scene Investigation had an original blog post on 2/28/13.

 

Tonight I'd like to talk about the mechanism behind the bloodshed involved in the first homicide in the elevator.  The deceased died of blood loss from a breached artery.

 

The human heart is a pump which circulates the blood throughout the body.  The blood carries oxygen and nutrients picked up in the lungs to the extremities so cells can be replenished.  This is done by way of the arteries in the body.

 

The arteries are much more muscular than the veins in order to withstand the blood pressure which propels the liquid blood through the vessels in order to reach those cells at the extremities.

 

When the heart pumps and blood is under pressure while traveling through the body, there is a classic pattern created called an arterial spurt when this pressurized blood "squirts" out the vessel where a hole or defect is created.

 

As the body begins to die and lose blood pressure, the 'pumps' of blood become less forceful and also contain less volume.  You can actually count the heart beats by the number of spurts and tell the sequence by the characteristics created by diminishing pressure and volume.

 

If you noticed the elevator walls, they tried to portray these arterial spurting patterns.  On a crime scene the telltale clue that it is arterial is the amount of volume propelled by force to create these patterns.  A splash may demonstrate the volume but not the force.  Expirated and impact patterns may demonstrate the force but not the volume.  

 

In bloodstain pattern analysis it always comes back to the size, the shape, and the distribution of the blood patterns and what mechanism or event can create stains with these characteristics.

 

Sometimes bloodstain pattern interpretation is like our elevator - it definitely has it's ups and downs!