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Questions and Answers
What type of crystals are formed in the Teichmann or Haematin Crystal Test?
What type of crystals are formed in the Teichmann or Haematin Crystal Test?
Which of the following tests is known for using a microspectroscope?
Which of the following tests is known for using a microspectroscope?
What do the blood-stain patterns help determine in a courtroom?
What do the blood-stain patterns help determine in a courtroom?
What does a positive result in the spectroscopic examination of recent blood stains show?
What does a positive result in the spectroscopic examination of recent blood stains show?
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Which blood grouping system was first discovered by Karl Landsteiner?
Which blood grouping system was first discovered by Karl Landsteiner?
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What is the primary purpose of forensic serology?
What is the primary purpose of forensic serology?
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Which test utilizes a positive reaction indicated by a blue color?
Which test utilizes a positive reaction indicated by a blue color?
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What type of evidence can blood and blood stains provide in a forensic investigation?
What type of evidence can blood and blood stains provide in a forensic investigation?
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Which component makes up about 65% of the total blood volume?
Which component makes up about 65% of the total blood volume?
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What is the significance of a negative preliminary test result in blood analysis?
What is the significance of a negative preliminary test result in blood analysis?
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Which of the following tests is specifically designed for urine and indicates a positive reaction by turning green?
Which of the following tests is specifically designed for urine and indicates a positive reaction by turning green?
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Which of the following tests produces light as a positive reaction rather than a color change?
Which of the following tests produces light as a positive reaction rather than a color change?
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What is one of the uses of blood in forensic investigations?
What is one of the uses of blood in forensic investigations?
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Study Notes
Forensic Serology - Biological Evidence
- Forensic serology examines and identifies biological evidence before individualization.
- Individualization confirms if a bodily fluid sample originates from a specific person.
Blood and Blood Stains - Applications
- Circumstantial evidence (prosecution/defense)
- Disputed parentage
- Determining cause of death/time of survival post-attack
- Determining direction of victim/assailant movement
- Establishing origin of blood flow
- Approximating time of crime
Blood Characteristics
- Circulating bodily fluid
- 1 cc blood contains 5,000,000 red blood cells
- Average adult has ~ 6 quarts of blood
- Composed of:
- Formed elements:
- Red Blood Cells (RBC)
- White Blood Cells (WBC)
- Platelets (thrombocytes)
- Plasma (liquid portion; ~ 65% of total blood volume)
- Formed elements:
- Serum: Straw-yellow liquid after blood clots
Preliminary (Presumptive) Blood Tests
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Positive result = possible blood; negative result = not blood
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Other substances can yield similar reactions (e.g., saliva, stomach juices), requiring confirmation.
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Benzidine: Blue color
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Guaiacum: Blue color
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Phenolphthalein (Kastle-Meyer): Red-pink
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Leucomalachite Green: Malachite green (bluish-green/peacock blue)
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Hematest: Green color
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Luminol: Produces light upon contact, useful for large-area screening
Confirmatory Blood Tests
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Essential for definitive confirmation as blood
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Establish presence of hemoglobin or its derivates
- Teichmann (or Haemin): Dark brown rhombic crystals
- Takayama (or Hemochromogen): Large salmon-pink rhombic crystals
- Wagenhaar (or Acetone-Hematin): Small dark circular crystals
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Spectroscopic Examination: Most reliable method; detects oxyhemoglobin (recent) and methemoglobin (old)
- Microspectroscope used for microscopic analysis
Blood Type Determination
- Necessary when human origin confirmed
- Blood group systems (especially ABO) help determine a person's blood type
Blood Evidence - Individual vs. Class
- Class evidence = blood type
- Individual evidence = DNA (if available)
Blood Stain Patterns
- Circumstantial evidence useful for argument
- Expert testimony can focus on:
- Direction of travel, perpetrator height
- Victim position
- Attacker's dominant hand
- Body movement/preservation status
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Description
Test your knowledge on forensic serology and the identification of biological evidence. This quiz covers applications of blood evidence, characteristics of blood, and preliminary blood tests used in forensic investigations. Gain insights into how blood evidence can be crucial in criminal cases.
