Questions and Answers
What type of evidence is blood typing?
Class evidence
What is the benefit of DNA STP analysis?
It provides a high degree of certainty regarding blood consistency.
What can we determine from blood spatter evidence?
The area of origin, direction, and angle of impact.
What type of tissue is blood?
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What are three functions of the blood?
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What are antibodies?
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In what type of blood cell will we find nuclei?
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Who made blood transfusion possible?
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What did Karl Landsteiner discover about blood?
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What is Rh factor?
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What is the significance of blood spatter analysis in forensic science?
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What chemicals must investigators spray to detect blood?
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What is the Kastle-Meyer test?
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How is blood evidence detected at a crime scene?
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What is the relationship between blood velocity and spatter size?
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What can blood spatter analysis reveal?
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What is passive bloodstains?
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What defines high velocity impact spatter?
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What is the significance of the pointed end of a blood droplet?
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What does the area of convergence help determine?
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What is the area of origin in blood spatter analysis?
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What are some factors that influence the shape of blood droplets?
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Study Notes
Blood Typing and Evidence
- Blood typing serves as class evidence, helpful in excluding suspects due to shared blood types among the population.
- DNA analysis of white blood cells (WBC) offers high certainty in matching crime scene blood with a suspect or victim.
Blood Spatter Analysis
- Blood spatter evidence reveals the area of origin, direction, and angle of impact of blood at a crime scene.
- Key aspects determined from blood patterns include direction of travel, angle of impact, area of origin, and potentially the death's circumstances.
Composition of Blood
- Blood comprises red blood cells, white blood cells, platelets, and plasma, which transports antibodies, hormones, nutrients, and minerals.
Historical Contributions
- William Harvey described blood circulation in 1650, unveiling its properties.
- Karl Landsteiner made significant strides in blood transfusion compatibility, discovering blood antigens and the risks of mismatched transfusions.
Blood Type Distribution in the U.S.
- The distribution of blood types includes O (43% Rh+ 85%), A (42% Rh- 15%), B (12%), and AB (3%).
Rh Factor
- The Rh factor, discovered in 1940, classifies blood as Rh+ (presence) or Rh- (absence) independent of A and B antigens.
Case Study: Ludwig Tessnow
- Tessnow's conviction for murder in 1901 involved blood evidence analysis that distinguished between human and animal blood.
History of Blood Spatter Analysis
- Edward Piotrowski first referenced blood spatter analysis in 1895; Dr. Victor Baltnazard advanced its understanding in 1939.
- Blood spatter analysis played a crucial role in the exoneration of Sam Shepard in 1955.
Forensic Blood Detection Techniques
- Investigators utilize UV light and reagents like luminol to detect blood traces, responding to hemoglobin.
- The Kastle-Meyer test detects hemoglobin and can identify other nickel and copper-based substances.
Blood Stain Types and Their Characteristics
- Passive stains are shaped by gravity, while projected stains result from applied force.
- Transfer stains occur when a bloody object contacts a surface.
Blood Drop Dynamics
- The shape and direction of blood droplets provide clues; the pointed end indicates travel direction.
- The size of blood droplets correlates with the velocity and type of violence inflicted (high, medium, or low velocity).
Patterns and Their Implications
- Arterial spurts are caused by heart pumping, while trails indicate movement.
- Evidence examined reveals the nature of the incident, potentially distinguishing between homicide and suicide.
Key Factors in Spatter Analysis
- Elements like gravity, cohesion, and surface tension influence blood droplet formation and spread.
- The angle of impact is calculable, providing insights into the spatial dynamics of a crime scene.
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Description
Explore the critical role of blood typing and blood spatter analysis in forensic science. This quiz covers the biological composition of blood, historical contributions to blood analysis, and the significance of blood evidence in crime scene investigations. Test your knowledge on these essential forensic topics.
