Who’s blood is it?. Forensic Characterization of Bloodstains Three questions to answer: 1. Is it blood ? 2. From what species did the blood originate? 3. If the blood is human , how closely can it be associated with a particular individual ?. How can a
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Who’s blood is it?
Forensic Characterization of Bloodstains
Three questions to answer:
1. Is it blood?
2. From what species did the blood originate?
3. If the blood is human, how closely can it be
associated with a particular individual?
How can a
be used for
Narrowing down our Persons of Interests
Summary of Results
Who’s blood is it?
Black Blond Red
hair hair hair
when a blood stain, hydrogen peroxide and phenolphthalein reagent are mixed,
the oxidation of the hemoglobin in the blood produces a deep pink color
(if 1 drop of blood were present in a bucket with 10,000 drops of water, the PHTH test would still turn pink)
hemoglobin - Blood contains hemoglobin (carries oxygen and makes blood red) which contains a heme group which contains an Fe which can catalyze the breakdown of hydrogen peroxide
The cell membrane of RBCs has molecules in its surface that act as identification badges so immune system can recognize it as a normal component.
Red Blood Cell
The differences in human blood are due to the presence or absence of certain chemicals called antigens. Individuals have different types and combinations of these chemicals.
Antigen = Antibody Generating Agent
Antigens are located on the surface of the red blood cells and the antibodies are in the blood plasma.
Blood Group A
If you belong to blood group A, you have A antigens on the surface of your red blood cells
Blood Group B
If you belong to blood group B, you have B antigens on the surface of your red blood cells
Blood Group AB
If you belong to blood group AB, you have both A and B antigens on the surface of your red blood cells
Blood Group O
If you belong to blood group O, you have no antigens on the surface of your red blood cells
Blood Group Notation
According to the above blood grouping systems you can belong to any of the following 8 blood groups
7. Record results in the data table. Answer with a YES or NO.
Type A blood
Crime Lab: Blood Analysis Unit
Name of Examiner: _____________
Blood Typing: Results for 4Suspect’s Blood Types
EVIDENCE BLOOD: TYPE O+
Summary of findings: