Bloodstain Patterns

Question 1

The theory of bloodstain patterns:

Answer 1

• Blood as a fluid responds to variations of internal and external forces in a predictable fashion.

Question 2

There are three underlying principles that guide the behavior of the behavior of the bloodstain pattern analyst:

Answer 2

• Pattern diversity principle
• Principle of stain shape and vector correlation
• Physically altered bloodstain (PAB) principle

Question 3

Blood spatter pattern categories are:

Answer 3

• Spatter stains and non-spatter stains

Question 4

The spatter category include patterns in which the primary stains are __________or__________. This includes some of the more probation patterns such as impact spatter, cast-off, spurts, drip trails and drips.

Answer 4

• Circular or elliptical

Question 5

The ______ blood category include all patterns where the primary stains are not circular or elliptical. They include patterns produced by contact, accumulation as well as some dynamic events such as blood into blood and gushes.

Answer 5

• Non-spatter

Question 6

Stains created when blood is ejected in a stream under pressure or with velocity, most often encountered when an artery or the heart is breached.

Answer 6

• Spurt

Question 7

Stains created when blood is flung from an object that is either in motion or which suddenly stops some motion.

Answer 7

• Cast- off

Question 8

A pattern of individual spatter deposited on a surface, demonstrating movement of the dripping item from one point to another.

Answer 8

• Drip trail

Question 9

A radiating pattern of small circular or elliptical shaped stains created when blood is broken up at a source by some force.

Answer 9

• Impact pattern

Question 10

Spatter resulting from blood dripping from an individual or otherwise bloodied object.

Answer 10

• Drip

Question 11

An irregular pattern created when blood is ejected in volume.

Answer 11

• Gush/splash

Question 12

A pattern of spatter deposited into another or into another liquid, resulting in an accumulation with secondary spatter randomly oriented around the margin.

Answer 12

• Blood into blood

Question 13

Any stain or pattern created by transfer of blood from one object onto another, through some form of contact.

Answer 13

• Smear

Question 14

Any stain or pattern created by the transfer of blood from one object to another in which a recognizable characteristic or image is present in the pattern.

Answer 14

• Pattern transfer

Question 15

Two primary field tests for the presence of blood:

Answer 15

• Leuco-malachite green

* Phenolphthalein

Question 16

Leuco-malachite and phenolphthalein are presumptive field tests for the presence of blood, which are based on:

Answer 16

• Oxidation-reduction reaction of chemicals that occurs in the presence of heme, a component of hemoglobin, which is the primary oxygen carrier found in red blood cells.

Positive reaction not conclusive since they react with other substances

Question 17

Luminol be used to to enhance latent bloodstains.

Answer 17

• Positive reaction to blood is typically blue-green, which lasts several minutes. Photographing requires a darkened area.

Question 18

Fluorescein can be used for the enhancement of latent bloodstains.

Answer 18

• Reacts to heme in blood and can be observed with alternate light sources between 455 and 485 nm which will fluoresce green

Question 19

Amigo-black can be used in enhancement of latent bloodstains:

Answer 19

• Reaction takes between about 3 minutes that is blue-black in color and should not be used on evidence items.

Effective for enveloping bloody footwear marks on a variety of scene surfaces such as floors and carpeting.

Question 20

The first sub-principle is directional angle. The collapse of a free flight droplet on a surface produces a stain with a circular or elliptical shape. These stains may have spines, scallops or satellite stains, which may define direction of travel for the droplet at moment of impact.

Answer 20

• Principle of Stain Shape and Vector Correlation

Question 21

The variations in combinations of blood volumes and forces acting on those volumes lead to recognizable classes of patterns.

Answer 21

• Pattern Diversity Principle

Question 22

Once exposed, blood will react to environmental conditions in a predictable manner (dries, wicks, permeates and coagulates on surfaces).

Answer 22

• Physically Altered Bloodstain Principle

Question 23

The area where reverse vectors of several related stains converge on a surface.

Answer 23

• Area of convergence