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Forensic investigations often yield evidence in crimes used to convict perpetrators.  If your story includes forensic investigations, be sure to research the method and means of gathering, handling and analyzing evidence.  The following notes were taken from The New Detectives, a documentary series on the Discovery Channel.  Real life cases are reenacted, providing excellent insight into the procedures of crime investigators.

A house is destroyed in a fire.  When arson investigators search the residence, they detect the smell of gasoline and the origin of the fire is inconsistent with an electrical fire. In fact, there were two sources of origin in the fire, an accelerant was used to start fires in the entry way and bedroom.

The home owner, Al Hamilton, was missing and his car was gone. An APB went out to field officers for Hamilton and his car.  In the meantime, crime scene investigators returned to the home and found a swipe stain, when a bloody object comes in contact with a non blood surface and police can determine direction of movement of the swipe.  Cast off stains were visible on the soot covered walls, preserved under the soot, indicating the fire was set after a bloody beating.

Using string and laser lights, investigators can determine the trajectory of the spatter to place the location of the victim at the time of attack. “A drop’s velocity, direction, and distance from the point of origin can be determined by its size and shape. As a general rule, the higher the energy of the impact, the smaller the drops are. Free-falling blood has a low velocity, leaving large drops. Impact spatters, found in cases of beating or stabbing, are medium-velocity.” (1)

Blood samples at the scene were confirmed to belong to Hamilton, who police believed was murdered. The only suspect was Ronny Richardson; an ex boyfriend of Hamilton’s fiancée, Donna Edwards.  The morning of the fire, Richardson went to Edward’s home and left several items, including tennis shoes he was wearing that day.

Investigators tested the shoes for residual ash, gas and debris that could be linked to Hamilton’s home.   

Donna cooperated with police, recording conversations with Richardson, including a confession. Richardson stashed the body in Edward’s car and hid the car where no one would find it.  He mistakenly believed that without a body, he would escape justice.

An abandoned car prompts a police search of nearby woods for June Atkins, reported missing the day before.  The search party discovered a bloodstained quilt and a pair of men’s work gloves, which smelled of gasoline. Crime scene technicians joined the search. Later in the day, a woman’s wallet was found, with Atkins’ identification. More blood was found in a grassy area.  The crime scene technicians took photos and collected samples from the area.  All of the evidence was sent to a crime lab for testing.

The first test done was a chemical color test to verify the substance was blood. The next test confirms the blood was human. The third test matches the samples taken from the crime scene to the victim.  In order to find a possible motive, deputies questioned friends and family members.

They discovered June met with Kenneth Pipkin on occasion.  A fisherman witnessed a woman and man in a pickup truck, which matched Pipkin’s vehicle. Police took fibers from Pipkin’s truck; which were compared to fiber evidence collected from the quilt found in the woods.  Despite the connection of Atkins to the bloody quilt and the quilt to Pipkin’s vehicle, prosecutors did not believe they had a strong enough case to try Kenneth Pipkin.

Blood Spatter Interpretation - Terms (2)

Angle of Impact  –  The acute angle formed between the direction of a blood drop and the plane of the surface it strikes.

Arterial Spurting (or gushing) Pattern  –  Bloodstain pattern(s) resulting from blood exiting the body under pressure from a breached artery.

Back Spatter –  Blood directed back towards the source of energy or force that caused the spatter.

Bloodstain  –  Evidence that liquid blood has come into contact with a surface.

Bubble Rings  –  Rings in blood that result when blood containing air bubbles dries and retains the bubble’s circular configuration as a dried outline.

Cast-Off Pattern  –  A bloodstain pattern created when blood is released or thrown from a blood-bearing object in motion.

Directionality  –  The directionality of a bloodstain or pattern which indicates the direction the blood was traveling when it impacted the target surface.  Directionality of a blood drop’s flight can usually be established from the geometric shape of its bloodstain.

Directionality Angle –  The angle between the long axis of a bloodstain and a predetermined line on the plane of the target surface which represents 0 degrees.

Direction of Flight  –  The trajectory of a blood drop which can be established by its angle of impact and directionality angle.

Draw-Back Effect  –  Blood in the barrel of a firearm that has been drawn backward into the muzzle.

Drip Pattern  — A bloodstain pattern which results from blood dripping into blood.

Expirated Blood  –  Blood that is blown out of the nose, mouth, or a wound as a result of air pressure and/or air flow which is the propelling force.

Flight Path –  The path of the blood drop, as it moves through space, from the impact site to the target.

Flow Pattern  –  A change in the shape and direction of a bloodstain due to the influence of gravity or movement of the object.

Forward Spatter  –  Blood which travels in the same direction as the source of energy or force which caused the spatter.

High Velocity Impact Spatter (HVIS)  — A bloodstain pattern caused by a high velocity impact /force to a blood source such as that produced by gunshot or high speed machinery.

Impact Pattern  –   Bloodstain pattern created when blood receives a blow or force resulting in the random dispersion of smaller drips of blood.

Impact Site  — That point where force encounters a source of blood.

Low Velocity Impact Spatter (LVIS)  –  A bloodstain pattern that is caused by a low velocity impact/force to a blood source.

Medium Velocity Impact Spatter (MVIS)  –  A bloodstain pattern caused by a medium velocity impact/force to a blood source.  A beating typically causes this type of spatter.

Misting  –  Blood which has been reduced to a fine spray, as a result of the energy or force applied to it.

Parent Drop — A drop of blood from which a wave, cast-off, or satellite spatter.

Passive Drop (Bleeding)  –  Bloodstain drop(s) created or formed by the force of gravity acting along.

Point (Area) of Convergence  –  The common point (area), on a two dimensional surface, over which the directionality of several blood drops can be retraced.

Point (Area) of Origin –  The common point (area) in a three dimensional space to which the trajectories of several blood drops can be retraced.

Projected Blood Pattern  –  A bloodstain pattern that is produced by blood released under pressure as opposed to an impact, such as arterial spurting.

Ricochet  –  The deflection of blood after impact with a target surface that results in straining of a second target surface.

Satellite Spatter  — Small droplets of blood that are distributed around a drop or pool of blood as a result of the blood impacting the target surface.

Perimeter Stain  –  A bloodstain that consists of only its outer periphery, the central area having been removed by wiping or flaking after liquid blood has partially or completely dried.

Spatter  –  That blood which has been dispersed as a result of force applied to a source of blood.  Patterns produced are often characteristic of the nature of the forces which created them.

Spine –  The pointed or elongated stains which radiate away from the central area of a bloodstain.

Swipe Pattern  — The transfer of blood from a moving source onto an unstained surface.  Direction of travel may be determined by the feathered edge.

Target  –  A surface upon which blood has been deposited.

Transfer/Contact Pattern  –  A bloodstain pattern created when a wet, bloody surface comes in contact with a second surface.  A recognizable image of all or portion of the original surface may be observed in the pattern.

Void  –  An absence of strains in an otherwise continuous bloodstain pattern.

Wave Cast-Off  — A small blood drop that originates from a parent drop of blood due to the wave-like action of the liquid in conjunction with striking a surface.

Wipe Pattern  — A bloodstain pattern created when an object moves through an existing stain, removing and/or altering its appearance.

Resources

1.  Ely, Catten: Blood Spatter - What Is It?, June 2000, (Retrieved January 2008)

2.  Bazoria County Sheriff: Blood Terminology (Retrieved January 2008)