Blood Spatter Analysis Presented by Patricia Nolan Bertino Bud Bertino

Blood Spatter (not splatter) is the pattern of blood created when blood is deposited on a surface.

Blood Detection Phenolphthalein Luminol

Blood spatter “tells a story” Where was person located when bleeding? What direction was blood traveling? What was the angle of impact?

What was the distance between bleeder and the striking surface? How many events occurred?

Is blood spatter evidence consistent with the story told by witness or suspect?

Simpson Crime Scene

Types of Injury High velocity (gunshot) Medium velocity (hammer strike) Low velocity ( drip)

Characteristics of a single drop of blood Spike vs. Satellite

Surface variations Smooth (glass) Slightly raised (floor tiling, varnished wood, fabric) Rough tile, unvarnished wood

Types of Blood Spatter Passive dripped blood Transferred hand print Projected artery bleed Cast off from a weapon

Transferred blood Footprint Handprint

Projected blood Arterial gush on wall

Blood dropped from different heights

Patterns of transfer ceiling Cast-off from Weapon

Direction of travel of blood

. Wave Cast-off Tail of elongated stain points in direction of travel Tail of wave cast-off points back to parent drop Parent drop wave cast-off

Point of Convergence 5 ml blood squirted from a syringe from height of 1 m Point of Convergence

Angle of Impact Origin Height above point of convergence Distance from point of convergence Height above point of convergence Origin length width Angle of impact = arc sin W/L 85 60 45 30

Angle of Impact 90 80 70 60 50 40 20 30 10 Path of blood W a Floor 20 30 10

Determine Angle of Impact Width Length sine arc sine 2 3 .6667 42° 1 4 .25 9.6 9.7 14.5° .9897 82.2° Hand-out

Point of Convergence

Lines of Convergence Draw line through the axis of the main droplet Start at the end of the blood drop and draw toward the source Do not draw lines through satellite drops Draw smallest circle around intersection -marks point of convergence

Lines of Convergence Determine Point of Convergence

Don’t over extend the lines! Draw towards the source of blood

Let’s practice! Floor demo worksheet

Answer Sheet for Lines of Convergence

Show Blood animations

Practice Paper Blood Droplets Draw lines of convergence Determine point of convergence Measure blood drop width/length Determine impact angle Can you determine point of origin?

Calculate Point of Origin Draw lines of convergence Determine point of convergence Determine impact angle Use protractor to determine origin Floor demo Or Use Law of Tangents

Law of Tangents (TOA) Opposite Adjacent Tangent of Angle = See page 19

Tracing Origin of Bloodspots Point of convergence 2 dimensional image Point of origin adds 3rd dimension to image In practice: use of string & protractor at scene use of computer at laboratory

Analyze crime scene pg 21 That’s all folks!