1. Serology, Blood and Blood Spatter
CHAPTER 12
Serology, Blood and Blood Spatter

2. INTRODUCTION Is blood class evidence or individual evidence?
What is the function of blood?
What information can be determined from a sample of blood?

3. What is Serology?
The term serology refers to a broad scope of laboratory tests that use specific antigen and serum antibody reactions.
Blood typing falls into this category.

4. BLOOD CONTENTS
Plasma
Mainly water, also proteins, hormones, antibodies, & nutrients
Red blood cells (Erythrocyes)
Carry O2 and CO2
Hemoglobin binds to O2 & makes blood red
White blood cells (Leukocytes)
Help with immune system
Only blood cell with a nucleus
Source of DNA
Serum
Platelets
Help with blood clotting

5. Add to your notes!
Plasma (or liquid portion of blood) makes up for 55%of the blood
Solid parts (red blood cells, white blood cells, platelets) makes up 45% of the blood

6. Important Parts for Forensic Science
Red Blood Cells—because of their importance in blood typing
Serum—because of its’ importance in carrying antibodies

7. BLOOD TYPING Less expensive than DNA profiling
Can’t match to an individual but can narrow down suspect list by blood type.
Karl Landsteiner developed system for classifying blood types in 1901.

8. BLOOD TYPING
Blood type is based on the presence or absence of proteins (antigens).
Proteins found on red blood cells
The two types of proteins are A and B

9. BLOOD TYPES Type A (42%) A protein Anti-B antibody Type B (12%)
B protein
Anti-A antibody

10. BLOOD TYPES Type AB (3%) Both A & B proteins No antibodies
Type O (43%)
No A or B proteins
Anti-A and Anti-B antibodies

12. Rh SYSTEM Rh factor is protein that is either present or not in blood
Also called D antigen
Rh + = Blood has Rh factor
Rh – = Blood does not have Rh factor
Majority of population is Rh+

14. Fundamental Principle of Blood Typing
Serum contains proteins known as antibodies
Antibodies are secreted by white blood cells to attack foreign invaders (antigens)
For every antigen, there is a specific antibody that reacts against it.
Anti-A reacts against antigen A
Anti-B reacts against antigen B
When antibodies react against its’ specific antigen, agglutination or clumping of RBCs occur. (Antigen-antibody response)

15. Blood Typing Tests Used to identify and match blood samples
3 separate tests are done
Mix blood with antibodies that bind to each protein (A, B, or Rh factor)
If agglutination occurs then the protein is present
Example
If agglutination occurs with protein A and Rh factor then the blood type must be? A+

16. Blood Typing Tests

17. Blood Typing Tests
Blood Type?
Blood Type? B- A+

18. Transfusions AB A and B None AB, A, B, and O A B A and AB A and O
Blood Group
Antigens
Antibodies
Can give blood to
Can receive blood from AB
A and B
None
AB, A, B, and O A B
A and AB
A and O
B and AB
B and O O
AB, A, B and O
Universal Acceptor
Universal Donor

19. Principles of Heredity
Antigens and enzymes are genetically controlled
Genes: responsible for transfer of hereditable material
Genes are found on chromosomes, which are found in the nucleus of every cell

20. Principles of Heredity
Human Cells contain 46 chromosomes with the exception of the egg and sperm, which contain only 23.
23 of these chromosomes are inherited from mother
23 of these chromosomes are inherited from father

21. Sex Chromosomes X-Chromosome: Female Sex Chromosome
Y-Chromosome: Male Sex Chromosome
XX individuals are female
XY individuals are male

22. Genes Come in Pairs
The position a gene occupies on a chromosome is called a locus.
Genes for the same trait are located at the same locus on both the mother and the father’s chromosomes.

23. Genes Come in Pairs
Alternative forms of genes that influence a given characteristic are called alleles.
Father: allele for brown eyes
Mother: allele for blue eyes

24. Gene Pairs
Made up of two similar genes AA: Homozygous “Homo” means the same Aa: Heterozygous “Hetero” means different

25. Blood Types are Genetic
A and B Blood Types are Dominant
Dominant: Characteristic is shown
Blood Type O is Recessive
Recessive: Characteristic is hidden
Recessive characteristics only appear when both alleles are recessive
Homozygous recessive OO

26. Phenotype V. Genotype Phenotype: individual’s outward characteristics
Genotype: individual’s pair of allele genes together
Example:
Phenotype Genotype
Type B Blood Could be BO or
BB depending
on parents

27. Alleles for Blood Types
Type A allele- A Type B allele- B Type O allele- O

28. Therefore…..
A person with the phenotype of Type A must have a genotype of AA or AO
A person with a phenotype of Type B must have a genotype of BB or BO
A person with a phenotype of Type AB must have a genotype of AB
A person with a phenotype of Type O must have a genotype of OO

29. Genotype of a child with Type B Blood must be BB
Punnett Squares
Mother: AB Father: BB A B B B AB BB B A
Genotype of a child with Type B Blood must be BB B B

30. Blood Spatter A group of bloodstains created when a wound is inflicted
Blood spatter patterns can give information about
Origin of the blood
Direction of blood
Cause of injury

31. Blood Spatter As blood leaves the body it falls with gravity Cohesion
Blood cells stick together as blood falls
Remains round when it lands
If parts of blood overcome cohesion then small secondary droplets will form known as satellites

32. Surface Type and Blood Smoother surface = smoother sphere of blood
Hard, smooth, non-porous surface
Example: glass, tile
little or no distortion around edges

33. Surface Type and Blood Rough or porous surface
Example: concrete, carpet
Greater distortion and satellites around the edges

34. Blood Spatter Patterns
1. Passive Fall
Blood falls as a result of gravity
Examples:
Blood dripping from a wound or weapon

35. Blood Spatter Patterns
2. Arterial spray or spurts
caused by pumping action of heart through damaged artery such as carotid artery in neck

36. Blood Spatter Patterns
3. Splashes
exclamation point pattern that can tell the position of the victim and direction of blood

37. Blood Spatter Patterns
4. Smears or transfer blood
When a bloody person comes into contact with another surface

38. Blood Spatter Patterns
5. Trails
Trail of blood drops or spurts

39. Blood Spatter Patterns
6. Pools of blood
forms around victim who is bleeding heavily in one spot

40. Blood Spatter Pattern 7. Cast-off stains
Blood thrown off a blood covered object
Usually occurs with repeated blows

41. Blood Spatter Patterns
8. High velocity blood spatter
Caused by a strong, explosive force
Example: gunshot, sneezing
Creates a misting of blood

42. Direction of Blood
If blood hits surface at 90º, then drop will be spherical
If blood hits at an angle of less than 90º, drop will elongate
Pointed end of blood stain will indicate the direction of travel

43. Direction of Blood
Direction of Blood

44. LINES OF CONVERGENCE Lines of convergence
Draw a line through the long axis of a group of blood stains to determine where they would intersect
2-D model

45. POINT OF ORIGIN Point of origin
Use of 2 or more spatter patterns to determine where the blood originated
3-D model

46. Crime Scene Investigation of Blood
If stain is found…
Is it blood?
Is it human?
Blood type
DNA

47. Is it blood? Preliminary test to determine if sample is blood.
Kastle-Meyer Test
Sample tested with phenolphthalein
Turns deep pink color Positive for blood
Hemastix
When moistened with distilled water and placed in contact with stain, a bright green color indicates blood.

48. Is it blood? Luminol Test
Produces light if blood is present in a darkened area
Extremely sensitive: can detect stains diluted up to 300X
Will not interfere with any subsequent DNA testing

49. LUMINOL

50. LUMINOL

51. Is it human blood? Precipitin Test:
Human blood is inserted into animal (rabbit)
Rabbits produce antibodies to react against the human blood
Blood is drawn from rabbit that contains the human antibodiesproduces human antiserum
Unknown blood sample, if human, will react with the human antiserum from the rabbit by forming a precipitate

53. Crime Scene Investigation of Blood
Interpret the findings
See if the blood type matches a suspect
If it doesn’t, excludes the suspect
If it does, decide if DNA profiling is needed

54. Collection and Preservation of Biological Evidence