FORENSIC BLOODSTAIN PATTERN ANALYSIS Blood Spatter Blood drops

FORENSIC BLOODSTAIN PATTERN ANALYSIS

Blood Spatter Blood drops form different shapes and sizes Blood spatter analysis uses the shapes and sizes to reconstruct the crime scene. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -2

Bloodstain Pattern Analysis Terms • Spatter – Bloodstains created from the application of force to the area where the blood originated. • Origin/Source – The place from where the blood spatter came from or originated. • Angle of Impact – The angle at which a blood droplet strikes a surface. Satellite Spatters • Parent Drop – The droplet from which a satellite spatter originates. • Satellite Spatters – Small drops of blood that break of from the parent spatter when the blood droplet hits a surface. • Spines – The pointed edges of a stain that radiate out from the spatter; can help determine the direction from which the blood traveled. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein Spin Parent Drop © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -3

Blood Stains Tell a Story • What 6 pieces of information could one deduce from the bloodstain pattern at a crime scene? – direction of blood origin, – angle the blood struck a surface, – location of a victim, – movement of a bleeding individual, – minimum number of blows on the victim – approximate location of the one delivering the blows FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -4

• • • Blood spatter shape is effected by volume of droplet Angle of impact force Velocity Height Surface texture – Smooth surfaces = smooth edges – Rough surfaces= rough edges FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -5

Blood Spatter--Volume Size of a blood drop depends on the volume (and height) of the drop. Volume depends on the object the blood originated from (needle = small; bat = large). FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -6

Determining Distance (height) Blood Falls § § § Drops form a circle when hitting surface Size depends on speed of blood drop and type of surface it hits Speed depends on distance (height) blood travels FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -7

Blood Fall Height • The higher the drop, the higher the velocity and the larger the diameter. Due to air resistance, speed maxes out at distances above about 7 feet FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -8

Velocity of Blood Spatter • After leaving the body, the velocity blood travels is referred to as low, medium, or high. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -9

Low Velocity Blood Spatters • The characteristics of a low velocity spatter are the pattern consists of large separate or compounded drops with diameters of 3 mm or more. Produced by minimal force and hits the surface with less than 5 ft/s velocity Dripping Blood from a wound. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -10

Medium Velocity Blood Splatters • The characteristics of a medium velocity spatter consists of small drops with diameters of 1 -3 mm. they travel at an average of 5 to 25 ft/s • They are commonly associated with blunt force trauma. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -11

High Velocity Blood Spatters • The characteristics of a high velocity spatter are that it consists of drops with diameters of less than 1 mm. This blood spatter hits at more than 100 ft /s. Gunshot spray. • Video FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -12

Arterial Spray Pattern • Arterial spray is caused by opening a major artery or the heart and it sprays out a large volume of blood with each heart beat. It has enough force to have a major spurted volume with flow patterns surrounded by radial spikes and satellite droplets. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -13

Effect of Surface § § Smooth surface = smooth sphere Rough surface may cause some splatter FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -14

Determining Direction of Blood Narrow end of a blood drop will point in the direction of travel. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -15

Determining Direction of Blood If more than one drop (from spatter) results, the point of origin can be determined FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -16

Stain Patterns of Blood • The origin of a blood spatter in a twodimensional configuration can be established by drawing straight lines through the long axis of several individual bloodstains. The intersection or point of convergence of the lines represents the origin point. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -17

Determining Direction of Blood This is a 2 -dimensional point of origin. It is possible to determine the 3 -D point of origin FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -18

Angled Impacts • The impact angle of blood on a flat surface can be determined by measuring the degree of circular distortion. At right angles the blood drop is circular, as the angle decreases, the stain becomes elongated. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -19

Blood Stains • Surface texture and the stain’s shape, size, and location must be considered when determining the direction, dropping distance, and angle of impact of a bloodstain. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -20

Stain Patterns of Blood • Surface texture is of paramount importance. In general, the harder and less porous the surface, the less spatter results. • The direction of travel of blood striking an object may be discerned because the pointed end of a bloodstain always faces its direction of travel. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -2121

Stain Patterns of Blood • A shooting may leave a distinct gunshot spattern. This may be characterized by both forward spatter from an exit wound and back spatter from an entrance wound. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -2222

Back Spatter from Gun Shot FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -23

Wound Characteristics • The location of injury, the size of the wound created, and the distance between the victim and the muzzle of the weapon all affect the amount of back spatter that occurs. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -24

Cast Off Patterns • A cast-off pattern is created when a blood-covered object flings blood in an arc onto a nearby surface. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -25

Expirated Patterns of Blood • A pattern created by blood that is expelled from the mouth or nose from an internal injury is called an expirated blood pattern. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -2626

A Void Pattern • A void is created when an object blocks the deposition of blood spatter onto a target surface or object. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -27

Transfer and Contact Patterns • When an object with blood on it touches one that does not have blood on it, this produces a contact or transfer pattern. • Examples of transfers with features include fingerprints, handprints, footwear prints, tool prints, and fabric prints in blood. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -28

Flow Patterns of Blood • Patterns made by drops or large amounts of blood flowing by the pull of gravity are called flows. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -2929

Trail Pattern of Bloodstains • A trail pattern is a series of drops that are separate from other patterns, formed by blood dripping off an object or injury FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -30

Documenting Bloodstain Evidence • Investigators should note, study, and photograph each pattern and drop of blood to accurately record the location of specific patterns and to distinguish the stains from which laboratory samples were taken. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -3131

Documentation The investigator should create photographs and sketches of the overall pattern to show the orientation of the pattern to the scene. FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -32

Blood Spatter Experts Video: Science of Murder: Blood Spatter https: //www. youtube. com/watch? v=Od 8 Yuw UT 794 FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein © 2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 10 -33