Determining the Cause of Different Patterns of Blood

SpatterHeather Anne Yeakel

To further understand the field of forensic science with regard to blood spatter

To discover whether or not weapons that cause blunt force trauma would create different patterns of blood spatter

Rationale

Blood spatter and the reasons spatter patterns differ was researched

Specifically, high, medium, and low velocity spatter and the different causes of these spatters

Blunt force trauma weapons mainly cause medium velocity spatter, that was researched further

Research

If a fist, plank of wood, and bat impact a sponge, then their spatter patterns will be both numerically and visually different

Hypothesis

1 Card Board Box 1 Sponge 1 Bat 1 Plank of Wood 1 Human Fist 1 Measurement Grid (3cm) White Paper Fake Blood

44 g of Corn Starch 80 mL water 160 mL Corn Syrup Red Food Coloring Green Food Coloring

Materials

Fake blood was created according to the recipe on the materials slide

For each trial a sponge was soaked in the blood solution and then placed in a cardboard box lined with white paper

The weapons were used to strike the sponge This was done three times with each weapon

and the paper was changed between each trial The spatters were then analyzed using a grid

system and the data was recorded

Procedure

Independent Variable◦ Weapon used to strike sponge

Dependant Variable◦ Spatter pattern created by weapon

Constant Variable◦ Set up of the box

Variables

Photos

Average Number of Blood Spatter

Fist Wood Bat

Back 0.02 11.41 20.2

Front Right 1.47 4.41 22.7

Front Left 0.85 14.27 18.13

Right Side 2.37 5.92 18.44

Left Side 7.57 23.07 21.14

Average Number of Spatters

Data

Back

Front Right

Front Left

Right Side

Left Side

0 5 10 15 20 25

Average Number of Blood Spatter

BatWoodFist

Standard Deviation

Fist Wood Bat

Back 0.17 22.94 20.05

Front Right 6.48 6.38 19.93

Front Left 12.37 24.4 17.14

Right Side 3.47 8.36 21.04

Left Side 2.35 18.86 14.89

Standard Deviation

P VALUES

Back Fist/ Back Wood 8.64E-17

Back Fist/ Back Bat 9.78E-50

Back Wood/ Back Bat 4.10E-07

Right Side Fist Right Side Wood 4.11E-06

Right side Fist/ Right Side Bat 2.55E-38

Right Side Wood/ Right Side Bat 4.80E-30

Left Side Fist/ Left Side Wood 1.55E-23

Left Side Fist/ Left Side Bat 3.78E-43

Left Side Wood/ Left Side Bat 8.11E-03

Right Front Fist/ Right Front Wood 7.28E-04

Right Front Fist/ Right Front Bat 1.53E-12

Right Front Wood/ Right Front Bat 4.04E-09

Left Front Fist/ Left Front Wood 3.56E-08

Left Front Fist/ Left Front Bat 4.52E-10

Left Front Wood/ Left Front Bat 0.50935217

T-TEST Results

A fist, a plank of wood, and a bat created different blood spatter patterns both visually and numerically

If further experimentation was to be done a device should be created to guide the weapon to the sponge to ensure the weapons impact the sponge at the same angle

To further expand on this topic this experiment could be preformed with weapons that create high velocity spatter

Conclusion

Force of impact Angle of impact The amount of blood soaked in the sponge The place where the sponge was struck

Sources of Error

Akin, L. L. (2004, May 23). Directional Analysis of Blood Spatter at Crime and Accident Scenes for the Private Investigator. Retrieved from http://www.akininc.com/ PDFs/ Directional%20Analysis%20for%20PI’s%20condensed.pdf

"Blood Spatter." World of Forensic Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. Gale Cengage, 2006. eNotes.com. 2006. 18 Oct, 2011 <http://www.enotes.com/forensic-science/blood-spatter>

Choosing A Baseball Bat. (n.d.). Retrieved 2008, from http://www.baseball-bats.net Crime Scene Reconstruction and Blood Spatter Analysis. (n.d.). Retrieved October 8, 2011, from

http://www.angelfire.com/ sc3/ cjrp/ csr.html Ely, Catten. “The Forensic Practice of Blood Spatter Interpretation.” suite 101. N.p., 14 June 2000.

Web. 30 Jan. 2012. <http://archive.suite101.com/ article.cfm/ crime_stories/ 34498>. Interpreting Blood Stain Patterns. (n.d.). Retrieved from Crime Scene Forensics LLC website:

http://www.crimescene-forensics.com/ Blood_Stains.html Lerner, E. K. L., Lerner, B. W., & Cengage, G. (2006). Blood Spatter. Retrieved October, 2011,

from http://www.enotes.com/ forensic-science/ Nelson, B. (2011, January 3). Blood Spatter. Retrieved from Deviant Crimes website:

http://www.deviantcrimes.com/ bloodspatter.htm Nowack, L., Collins, R., Li, G., Carter, A., Illes, M., Gorman, V., . . . Stotesbury, T. (2011, November

3). Computer Analysis of Blood Stain Patterns on Angled Surfaces [Informative Journal ]. Retrieved from http://www.iabpa.org/ JBPA%20Sept%202011.pdf

Reynolds, M. (n.d.). Blood Spatter. Forensic Investigations. Retrieved from http://www.clt.uwa.edu.au/ __data/ page/ 112508/ fsb05.pdf

Refrences