WARM UP 4/12 2. What can a gunshot wound show? 3. Give 3 things that can show a drowning. 4. What bone breaks during a hanging? 5. What is a contusion? 6. What is an incised wound? 7. What in the eyes can show signs of asphyxiation? 8. What are some signs of a close range shooting?

Ch 2 NOTES #5 BLOOD AS EVIDENCE 3/24

FORENSIC SEROLOGY The study of blood and how it applies to the law

BLOOD FACTS Main function is to carry oxygen and nutrients around the body Average person has 6 liters of blood Lose about 2.6 liters and life threatening Made in bone marrow

BLOOD IS MADE OF: 1. PLASMA – yellowish fluid portion making up 55% of the blood 2. ERYTHROCYTES – (red blood cells) - 1,000,000 per drop - carries nutrient, O2, CO2, and wastes - protein hemoglobin contains iron to help carry O2; gives color 3. LEUKOCYTES – (white blood cells) - defends against bacteria, viruses, etc. - produce antibodies or kill microbes themselves 4. PLATELETS – helps form blood clots - hemophilia

RED BLOOD CELL

WHITE BLOOD CELL

PLATELET

BLOOD TYPING In 1901, Karl Landsteiner discovered that there were 4 different blood types: A, B, AB, and O He named it the A-B-O system This helped understand why people were dying after transfusions or receiving blood

BLOOD TYPE IF CLUMPS WITH…. A Anti-A B Anti-B AB Anti-A and anti-B O No clumping

BLOOD TYPE IS CLASS EVIDENCE – narrowed down to a group of people FOUR BLOOD TYPES: A (40% of population) B (11%) AB (4%) O (45%) ****Presence or absence of A and B antigens on red blood cell surface determines blood type.

*A 5th blood protein was discovered – Rh factor Rh + present 85% of Americans Rh - not present 15% of Americans

About 80% of the population are secretors Secretors secrete their blood antigens into their tears, sweat, semen and saliva The presence of any of these substances permits identification of the blood type of the suspect Knowing the blood type allows you to rule out suspects rather than identify them. Why?

VIDEO CLIP

TESTS ON BLOOD Determine if it is blood a. KASTLE-MEYER COLOR TEST *hemoglobin (protein in blood that carries oxygen) turns deep pink

b. HEMISTIX – strips, moisten, touch stain – turn green if blood c. LUMINOL – spray, produces light if blood (even if diluted 10,000 X)                        Suspected bloodstain  on cloth? Reveal by spraying with  luminol in the dark

Determine if it is human a. PRECIPITIN TEST * human anti-serum – antibody for human blood will react with blood and form white solid * can be used on dried blood years old

BLOOD SPATTER What you can tell… DIRECTION IT HIT 2. ANGLE HIT

HOW HARD IT HIT AREA AND # TIMES IT HIT SURFACE

HEIGHT IT FELL FROM 6. EVENTS OF THE CRIME