Blood and Body Fluids

Question 1

What are the common types of body fluids in crime scenes?

Answer 1

Blood
Semen
Saliva

Question 2

What are the less likely types of body fluids examined at a crime scene?

Answer 2

Sweat
Urine (toxicology)
Faeces (bacterial_

Question 3

What does a crime lab do?

Answer 3

Presence of body fluids, blood pattern analysis (preliminary testing)

Question 4

What circumstances is blood analysis used?

Answer 4

Assault/murder, injury to suspect (blood pattern analysis)

Question 5

What circumstances is semen analysis used?

Answer 5

Sexual assault

Question 6

What circumstances is saliva analysis used?

Answer 6

Sexual assault
Bites
Saliva on mask

Question 7

How is blood extracted from a sample?

Answer 7

Rub filter paper

Question 8

How is semen and saliva extracted from a sample?

Answer 8

Damp blotting paper

Question 9

What is the initial Characterisation of blood?

Answer 9

Sample blood?- preliminary tests i.e. luminol test
Sample animal blood? i.e. precipitant test
Animal blood, what species i.e. anti-serum
Human blood- what type?
Sex (chromosome testing, testosterone), age and race of source (clotting crystallisation)

Question 10

What are the preliminary tests for blood for Leuchomalchite Green?

Answer 10

LMG (reduced) –Test stain +H2O2-> LMG (oxidised)
Colour change to blue/green
Hydrogen peroxide

Question 11

What are the preliminary tests for blood for Kastle Meyer?

Answer 11

Phenolphthalein (reduced)-Test stain +H2O2-> Phenolphthalein (oxidised)

Question 12

What are the preliminary tests for blood for Luminol?

Answer 12

3-aminophthallyhydrazide
Chemiluminescence in the presence of Hb
Luminol + H2O2 -> 3-aminophthalate (light producing reaction)
Shows hidden crime scenes i.e. may not have seen blood present, luminol highlights this
Nothing vanishes without a trace
Discovery can lead to more evidence i.e. blood soaked through carpet, provides more sample
Problems- luminol can lead to destruction of other evidence e.g. footprints and fingerprints
Thinks like bleach and saliva can provide a false positive

Question 13

What is microscopy used for in testing semen?

Answer 13

Large amount of DNA present, treat with staining reagent, high power microscopy

Question 14

How long is semen present after an incident?

Answer 14

5 days

Question 15

What does Acid Phosphatase do in the presence of semen?

Answer 15

Purple colour is produced, also present in vaginal fluid (small quantities)

Question 16

What is the preliminary testing for saliva?

Answer 16

Starch/Iodine- turns blue/black in present of starch
Salivary Amylase- saliva breaks down starch (no blue/black colour) broken down to monosaccharides
Saliva may contain bacterial/cheek cells (DNA profiling)

Question 17

What does blood pattern analysis analyse?

Answer 17

Examination of shapes, location and distribution of blood stains, in order to provide an interpretation of the physical events which gave rise to the origin

Question 18

How can blood pattern analysis provide information regarding sequence of events?

Answer 18

Position of the victim

Evidence of struggle

Question 19

How can blood pattern analysis provide evidence to corroborate or refute statements made by those involved?

Answer 19

Stain patterns on suspects clothing

Stain patterns on victim/ at scene

Question 20

What are the types of patterns?

Answer 20

Passive
Transfer
Projected

Question 21

What is Passive patterns?

Answer 21

Due to gravity
Drops
Drips
Pools 
Clots
Shape affected by target surface texture
Smooth vs. rough surfaces

Question 22

What is Transfer patterns?

Answer 22

Wet bloody surface in contact with another surface produces a pattern
Contact
Swipe/smear
Wipe
Smudge

Question 23

What is Projected patterns?

Answer 23

Arterial spurt/gush- blood exiting at high pressure & velocity
Cast of stains- comes from weapon, goes in an ark
Impact: low, medium, high velocity
Point of convergence- point of impact, where victim may have been lying

Question 24

What is the importance of blood grouping?

Answer 24

Still used in many countries
Historical cases
Large samples eliminated by quick inexpensive screening
Discovery of more systems inherited independently of each other and ABO- particular crime suspect type A other blood types can be ruled out

Question 25

What are the immunological systems?

Answer 25

Protein variants
Groups
Elimination
Increase typing systems-decrease the number of people sharing the combination
Quantity of blood may be limited- limited analysis
Analysis time consuming

Question 26

What are the Immunological biological markers?

Answer 26

ABO 
Rhesus
MNS
Duffy
Km

Question 27

What are the protein biological markers?

Answer 27

ACE (Acetylcholine Esterase)
ACP (Acid Phosphatase)
Haemoglobin
PGM (Phosphoglucomutase)

Question 28

What antigens are present in people with blood type A?

Answer 28

A

Question 29

What type of antibodies are present in the serum in blood type A?

Answer 29

Anti-B

Question 30

What antigens are present in people with blood type B?

Answer 30

B

Question 31

What type of antibodies are present in the serum in blood type B?

Answer 31

Anti-A

Question 32

What antigens are present in people with blood type AB?

Answer 32

AB

Question 33

What type of antibodies are present in the serum in blood type AB?

Answer 33

Neither anti-A or anti-B

Question 34

What antigens are present in people with blood type O?

Answer 34

Neither A or B

Question 35

What type of antibodies are present in the serum in blood type O?

Answer 35

Both anti-A and anti-B

Question 36

What are examples of blood proteins?

Answer 36

Polymorphines
Iso-enzymes
E.g. Hb- sickle-cell anaemia
Probability

Question 37

What percentage of the population are secretors?

Answer 37

75-85%

Question 38

What do secretors have?

Answer 38

Higher concentration of A and B antigens