Chapter 2: Crime Scene Bloodstain Pattern Analysis

Blood

a bodily fluid circulating within the body.

8%

An average adult has a blood volume of approximately ______ of his or her body weight.

plasma

Blood consists of a cellular portion as well as a liquid portion known as _____.

Cellular Portion

______ consists of blood cells and platelets.

Plasma

It is mostly composed of water and other substances such as proteins, inorganic salts, and other organic substances.

blood coagulation

Blood can form clots (or thrombi) that are the result of ________Blo.

Blood Viscosity

A measure of the blood’s resistance to flow.

Surface tension

______ causes liquids to minimize their surface, making the formed blood drop spherical.

distortion

Bloodstains that land on porous or rough surfaces usually have more _____ around the edges of the stains than those that land on smooth surfaces.

chemical enhancement reagents

Many chemical reagents react with blood to exhibit a color, a chemiluminescent light, or a fluorescent light. These tests are extremely sensitive and thus are used as __________ for detecting bloodstains.

Luminol

Used for locating bloodstains at the scene.

presumptive tests

Other reagents such as phenolphthalein, leucomalachite green, and tetramethylbenzidine are not often used as enhancement reagents but rather as *_______* for blood.

overall photograph

An _____ provides an overall view of the scene including the bloodstain evidence.

midrange photograph

A _____A close-up photograph, usually taken with a macro lens, provides a detailed image of single bloodstains, which is useful for spatter pattern analysis. provides more details of the bloodstain pattern compared with that of the overall photograph.

close-up photograph

A _______, usually taken with a macro lens, provides a detailed image of single bloodstains, which is useful for spatter pattern analysis.

Spatter Stain

A bloodstain resulting from a blood drop dispersed through the air due to an external force applied to a source of liquid blood.

Low Velocity Impact Spatter

Formed when a blood droplet is traveling at

Medium Velocity Impact Spatter

Formed when in a blood source is subjected to a force associated with beatings or stabbings. The resulting stains range from 1 to 4 mm in diameter.

High Velocity Impact Spatter

Formed when a blood source is subjected to a force associated with shooting using firearms. The resulting stains are usually

Directionality

The characteristic of a bloodstain that indicates the direction blood was moving at the time of deposition.

Parent Stain

The resulting spatter stain is an elongated ellipse.

Satellite Stain

A smaller bloodstain that originated during the formation of the parent stain as a result of blood impacting a surface.

Angles of Impact

The acute angle (alpha), relative to the plane of a target at which a blood drop strikes the target.

circular parent stain

When a blood drop lands on a surface at a *perpendicular angle* (90°), a ________ is formed, where the length and the width of the stain are equal.

elongated

When a blood drop is projected onto a surface at an *angle of between 0° and 90°*, the stain is _______.

Area of Origin

The three-dimensional location from which spatter originated. It can be determined based on the measurements from multiple elongated spatter stains.

String Method

In the ______, multiple well-formed, elongated spatter stains are selected for analysis.

Tangent Method

In the _____, the directionality of a single stain is determined first.

Area of Convergence

The area containing the intersections generated by lines drawn through the long axes of individual stains that indicates in two dimensions the location of the blood source.

Passive Blood Stains

It is formed due to bleeding from wounds, and the blood is deposited on a surface by the influence of the force of gravity alone.

Drip Stain

Formed when a falling drop of blood from an exposed wound or a blood-bearing object lands on a surface.

drip trail

If a blood source is moving, a ______ is formed.

Drip Pattern

Formed when a liquid drips into another liquid, where one or both of the liquids are blood.

Splash Pattern

Formed when a volume of blood spills onto a surface. It usually has large stains surrounded by numerous, peripheral, elongated bloodstains.

Flow Pattern

Caused by the movement of a large volume of blood on a surface either due to gravity or to the movement of the target such as a victim or postmortem disturbance.

Pool

A bloodstain resulting from the accumulation of liquid blood on a surface.

gelatinous blood

If blood is coagulated, ________ clots can be observed.

Serum stain

Which consists of the liquid portion of the blood after a clot is formed, may also be present.

Transfer Bloodstain

A bloodstain resulting from contact between a blood-bearing surface and another surface.

Swipe Pattern

A bloodstain pattern resulting from the transfer of blood from a blood-bearing surface onto another surface, with characteristics that indicate relative motion between the two surfaces.

Wipe Pattern

An altered bloodstain pattern resulting from an object moving through a preexisting wet bloodstain.

Perimeter Stain

A type of wipe pattern, is a bloodstain that is disturbed before it is dried but it maintains the peripheral characteristics of the original stain.

Projected Bloodstain

Formed when a volume of blood is deposited on a surface under a pressure or a force that is greater than the force of gravity.

Impact Pattern

Formed when an object strikes liquid blood.

Cast-Off Pattern

Formed when blood drops are released from a moving blood-bearing object.

Forward Spatter

Formed when blood drops travel from an exit wound in the same direction as a projectile.

Back Spatter

Formed when blood drops travel from an entry wound in the opposite direction of a projectile.

Expiration Pattern

Formed when blood is forced by airflow through the trachea and out of the nose or mouth.

Arterial Spurt Pattern

Associated with wounds damaging arterial blood vessels where blood stains are driven by arterial pressure.

void pattern

At a crime scene, if the projectile of bloodstains is blocked by an object, a ________ is formed, which exhibits an area where there is an absence of blood surrounded by continuously distributed bloodstains