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!