Blood

Alexandra Bowles

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How is blood useful in forensics?

Blood typing, when conducted accurately, is a valuable piece of evidence for forensic nurses, helping to pinpoint individuals and their relation to the crime. Human blood includes over 100 different antigens, which could be impractical and time-consuming to test for each antigen during the already-complicated process of crime solution. LNCs instead incorporate a number of different blood testing techniques, specifically the ABO system, which involves examining the surface of the red blood cells for two antigens known as A and B, with blood type being named after the type of antigens it contains, including A, B, AB and O. The basic foundation of serology states that for every antigen, a specific antibody is in existence.

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Why is it important?

Blood is the most common and possibly most important evidence in the solving of certain types of crimes. Nothing has been found to provide a better substitute for blood analysis. Its presence has the keen ability to link a suspect and a victim, or a suspect to a location.
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Famous Cases

The Sam Sheppard Case:

Blood and blood-spatter analysis is used to suggest probable doubt as to Sheppard's guilt that he beat his wife to death. This is one of the first cases blood is in forensic analysis.

https://samsheppardmurdercase.wikispaces.com/Forensic+Techniques+employed+to+detect+and+process+such+evidence


The Christopher Vaughn Case:

Blood-spatter analysis was used to disprove Vaughn's story of the crime and prove his guilt.

http://articles.chicagotribune.com/2012-09-12/news/ct-met-christopher-vaughn-trial-0912-20120912_1_christopher-vaughn-vaughn-story-seat-belt


The Mya Lyons Murder:

Blood-spatter analysis shows evidence that Mya Lyons was killed inside her father's van which does not line up with the father's story.

http://articles.chicagotribune.com/2011-01-19/news/ct-met-mya-lyons-charges-20110118_1_mya-ericka-barnes-richard-lyons-bellow

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Fun Facts About Blood

1. Blood makes up around 7% of the weight of a human body.
2. Grouping human blood types can be a difficult process and there are currently around 30 recognized blood types (or blood groups). You might be familiar with the more simplified “ABO” system which categorizes blood types under O, A, B and AB. Do you know which blood type you are?
3. Red blood cells have the important job of carrying oxygen around the body. They also contain a protein called hemoglobin. Hemoglobin contains iron which combines with oxygen to give hemoglobin and our blood, a red color.
4. The gravitational pooling of blood, called livor mortis, can indicate a victim’s time of death by analyzing the discoloration in the lowest point in the body.
5. The first modern study of blood stains occurred in 1895.
6. Blood pattern analysis is perhaps most often used to confirm or refute the statements of witnesses or suspects present at the commission of a crime.
7. A human must lose approximately 40% of his or her total blood volume before they are at risk for death from blood loss.
8. Rh stands for rhesus monkeys, in whose blood this antigen was first found.
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Definitions: Do you know blood?

Serology

Serology is the study and examination of bodily fluids that is used in forensic science as a means of segregating fluids excreted by assailants or attackers in varying criminal acts.


One important aspect of Serology is determining whether or not stains resembling blood found at a crime scene are actually blood or some other stain that bears a similar resemblance.

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Plasma

The liquid part of the blood and lymphatic fluid, which makes up about half of the volume of blood. Blood plasma contains antibodies and other proteins. The most fluid portion of blood consists of plasma, which is mostly water, and serum, which is yellowish and contains white cells and platelets.
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Antibodies

Antibodies, also known as immunoglobulins, are Y-shaped proteins that are produced by the immune system to help stop intruders from harming the body. With red cells, the analyst looks for smaller substances residing on their surfaces, such as antigens, which have important forensic implications. One might even say that forensic serology is all about antigens and antibodies
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Antigens

Antigens are any foreign substance or cell in the body that reacts with antibodies. Around 1937, scientists discovered a series of antigen-antibody reactions in blood. More than 100 antigens exist with 23 blood group systems based on these antigens.
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Erythrocytes

A red blood cell. The most abundant cells in our blood; they are produced in the bone marrow and contain a protein called hemoglobin that carries oxygen to our cells.
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ABO

a system for classifying human blood on the basis of antigenic components of red blood cells and their corresponding antibodies. In 1901, Karl Landsteiner discovered ABO blood groups. In 1904, a case was closed due to Landsteiner’s research and the birth of blood analysis was born.
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Rh

Rh factor: An antigen found on the surface of red blood cells. Red blood cells with the antigen are said to be Rh positive (Rh+). Those without the surface antigen are said to be Rh negative (Rh-).
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Leukocytes

White blood cell, also called leukocyte or white corpuscle,that lacks hemoglobin, has a nucleus, and defends the body against infection and disease.
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Platelets

An irregularly shaped cell-like particle in the blood that is an important part of blood clotting. Platelets are activated when an injury causes a blood vessel to break.
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Hemoglobin

The oxygen-carrying pigment and predominant protein in the red blood cells. In 1863, The German scientist Schönbein first discovered the ability of hemoglobin to oxidize hydrogen peroxide making it foam. This resulted in the first presumptive test for blood.
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Blood factors

The makeup of ones blood that describes the differences in it such as Rh.
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Serum

The liquid part of the blood with the protein which forms during clotting removed. With serum, the analyst can determine the freshness of a blood sample because serum clots several minutes after exposure to air
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