Blood can provide important evidence at crime scenes. Blood group/type can place a blood sample within a class of individuals, while DNA profiling allows a blood sample to match a single individual. Blood splatter patterns can also help reconstruct a crime scene by indicating how the blood was deposited and the movement and location of its source.

1. DRYSDALE CSI
Blood and blood splatter.
Ian Anderson
Saint Ignatius College Geelong

2. WHAT IS BLOOD?

Blood left at a crime scene can be analysed in
several ways.
Blood group/type can provide class evidence.
 DNA profiling can determine whether blood left at a
crime scene belongs matches the blood of a suspect (or
victim).
 Blood splatter can be used to help recreate a crime
scene.

http://dungenie.com/forums/forum_posts.asp?TID=10639&PN=10

3. WHAT IS BLOOD?
Average adult has about 5-6L of blood in their body.
 Makes up approximately 9% of our body weight.

http://www.english-online.at/biology/blood/blood-supply-and-blood-diseases.htm

4. WHAT IS BLOOD?

Blood is composed of

Red blood cells (erythrocytes).


Carry oxygen to cells and carbon dioxide away from cells.
White blood cells (leucocytes).
Several different types.
 Involved in defence and immunity
 fighting pathogens (disease causing organisms)


Platelets.


Involved in blood clotting.
Plasma.

90% water and remainder made up of dissolved proteins,
hormones, sugars, amino acids, vitamins, minerals, urea,
antibodies, etc.

5. WHAT IS BLOOD?

Blood has several important functions, including





Carries oxygen to cells.
Carries waste (including carbon dioxide, urea & lactic
acid) away from cells.
Carries disease fighting cells.
Involved in blood clotting.
Involved in homeostasis.
Regulation of body pH.
 Regulation of core body temperature.


6. BLOOD GROUPS.
Blood from one person does not always freely mix
with blood from another person. Instead, clumping
might occur, which can result in death.
 In 1901 Karl Landsteiner found that this response
was due to the presence or absence of antigens
(proteins on the surface of red blood cells), and is
now used to classify a person’s blood type (ABO
system).

A = only has antigen A.
 B = only has antigen B.
 AB = has both antigens A and B.
 O = has neither antigens A or B.


7. BLOOD GROUPS.

These blood types contain antibodies that react
against the antigens.
Blood group
Antibody in plasma
A
A antigen
anti-B
B
B antigen
anti-A
AB
A & B antigens
no antibodies
O

Red blood cells contain
no antigens
anti-A & anti-B
Every person belongs to one of these four blood
groups for their whole life.

8. BLOOD GROUPS.

These blood types contain antibodies that react against the
antigens.
Blood Group
Population
A
B
AB
O
Aborigines
0
0
34
Australian
(nonaboriginal)
39
11
4
46
UK/USA
41
10
4
45
Polynesian
52
0
0
48
Peruvian
Indian

66
0
0
0
100
Your blood type is not necessarily unique to you, but is
associated with a group of people.

Therefore blood type is regarded as class evidence.

9. BLOOD GROUPS.

Other blood grouping factors are also now used,
incl.

Rh factor.


MN proteins.


~82% of Australians Rh+ and 18% are Rh-.
~30% of people MM, 22%NN, 48% MN.
Combining these other blood grouping factors,
somebody can now be placed into one of 288
different blood types.
http://www.smosh.com/smosh-pit/articles/blood-typing-japanese-zodiac

10. DNA PROFILING.
DNA collected from white blood cells can be used
for DNA profiling (also called DNA fingerprinting).
 DNA profiling allows a blood sample to be identified
with a single person.

http://blog.canacad.ac.jp/bio/BiologyIBHL1/1298.html

11. BLOOD SPLATTER.
When a wound is inflicted and blood leaves the
body, a blood splatter pattern may be created. This
pattern can then be used to help reconstruct the
series of events surround the shooting, stabbing or
beating.
 The characteristics of blood drops on surfaces can

Show how the blood was deposited
 At what rate the blood was moving
 The location of the origin or source of blood
 The direction in which the blood was moving when it
struck the surface.


12. BLOOD SPLATTER.