FORENSICS OF BLOOD

BY : CYNDREKA LINDSEY

CHEM-4201

11/20/2014

OUTLINE

• BACKGROUND

• SPATTER ANALYSIS

• BLOOD PATTERNS

• COMMON TESTS

• WRITING ASSIGNMENT

• QUESTIONS

BACKGROUND

• BEFORE BLOOD ANALYSIS DETECTIVES HAD TO RELAY ON THEIR INSTINCTS AND CRIMINAL CONFESSIONS TO SOLVE A CRIME

• SEROLOGY: THE EFFECTS OF SERUMS AND THE ANALYSIS OF ITS PROPERTIES

• BLOOD, SEMEN, SWEAT, SALIVA

• WHEN STRUCK WITH A CERTAIN AMOUNT OF FORCE BODIES LEAK OR SPRAY BLOOD AND THE BLOOD IN FLIGHT TENDS TO BE UNAFFECTED BY

• TEMPERATURE, HUMIDITY, OR ATMOSPHERIC PRESSURE.

• BLOOD EVIDENCE IS FOUND IN CRIMES OF VIOLENCE :

• HOMICIDE, ASSAULT, AND SEXUAL ASSAULT.

•  IT MAY BE IN THE FORM OF FRESH LIQUID, COAGULATED, DRIED, OR AS A SMALL DROP OR STAIN, AND EACH FORM INVOLVES A DIFFERENT METHOD OF PRESERVATION AND COLLECTION.

BLOOD SPATTER PATTERNSTransfer Swipe Pattern:• Movement from stained

to unstained surface

Transfer Wipe Pattern:• Moves through an existing

stained surface

Spatter Pattern:• Created by force and

travels through air before hitting surface

BLOOD SPATTER ANALYSISLow Velocity Blood Spatter:• Blood that falls at the

speed or force of normal gravity

Medium Velocity Blood Spatter:• Produced with more

energy than the force of normal gravity

High Velocity Blood Spatter:• The force should be greater than

100 feet per second (high speed collisions)

COMMON TESTS FOR BLOOD….

BENZIDINE TEST • Benzidine is prepared from nitrobenzene in a two step process• [5,5] Sigmatropic Rearrangement

LEUCOMALACHITE GREEN(LMG)

• The condensation of benzaldehyde and dimethylaniline to give Leucomalachite gree is how Malachite green is prepared

KASTLE-MEYER TEST (KM)

• A potential blood sample is treated with phenolphthalein and it turns pink due to an oxidation reaction

HEMASTIX TEST

The test is based on the peroxidase-like activity of blood which has the ability to cleave oxygen molecules from H2O2 and catalyze the reaction from the reduced colorless form of 3,3’,5,5’-tetramethylbenzidine to the oxidized colored form

LUMINOL TEST

• An oxidizing agent, such as blood, catalyzes the oxidation of luminol by hydrogen peroxide in a basic solution and the light emitted in the luminol reaction is the result of a positive test.

WRITING ASSIGNMENT….

• RECREATION OF A FAMOUS BRUTAL CRIME SCENE (OJ SIMPSON MURDER CASE)

• WILL BE A VISUAL DISPLAY ON THE BLOOD PATTERN AND SPATTER IN THREE DIFFERENT SCENES

• FROM MY DISPLAY THE CLASS SHOULD BE ABLE TO IDENTIFY (IF ANY):

• WHAT PRESUMPTIVE TEST TO USE?

• WHAT IS THE PATTERN OF THE BLOOD?

• WHAT IS THE SPATTER VELOCITY OF THE BLOOD?

• WHAT OBJECTS COULD HAVE BEEN USED IN THIS CRIME?

• WAS THERE ANY CLEAN UP OF THE BLOOD?

REFERENCES

• BEVEL, TOM AND GARDNER, ROSS M. BLOODSTAIN PATTERN ANALYSIS, 2ND ED. CRC PRESS: BOCA RATON, FL, 2002.

• JAMES, STUART H. AND NORDBY, JON J. FORENSIC SCIENCE: AN INTRODUCTION TO SCIENTIFIC AND INVESTIGATIVE TECHNIQUES, 2ND ED. CRC PRESS: BOCA RATON, FL, 2005.

• SAFERSTEIN, RICHARD. CRIMINALISTICS: AN INTRODUCTION TO FORENSIC SCIENCE. PEARSON PRENTICE HALL: SADDLE RIVER, NJ, 2004

• BLOOD TYPE HTTP://EN.WIKIPEDIA.ORG/WIKI/BLOOD_TYPE

• BLOOD PLASMA HTTP://EN.WIKIPEDIA.ORG/WIKI/BLOOD_PLASMA

• FORENSIC INVESTIGATIONS—BLOOD SPATTER: ALL ABOUT BLOOD WWW.CLT.UWA.EDU.AU/__DATA/PAGE/112508/ FSB04.PDF

QUESTIONS?