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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?