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Forensics > Body Fluids > Flashcards

Body Fluids Flashcards

1
Q

Typical fluids to be analysed

A

Blood
Semen
Salivia

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2
Q

Less likely fluids to be analysed

A

Sweat
Urine (pregnancy, toxicology)
Faeces

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3
Q

What do body fluids show?

A

Blood- assault, murder, injury to suspect
Semen- sexual assault
Salivia- sexual assault, bites (food and skin), mask?

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4
Q

How is blood extracted from a sample?

A

Rub filter paper

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5
Q

How are semen and saliva extracted from a sample?

A

Damp blotting paper

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6
Q

Blood characterisation

A

Is the sample blood? Preliminary testing
Is the sample human/animal? Precipitant test
What species of animal? Anti-serum
What type of human blood? Chromosome testing (sex), testosterone (sex), clotting and crystallisation (age)

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7
Q

preliminary testing for blood?

A

Not entirely specific
Prone to false reactions
Red blood cells and platelets in blood have no DNA

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8
Q

What are the three preliminary tests for blood?

A

LMG
Kastle Meyer Test
Luminol

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9
Q

Haemoglobin acts like a catalyst in the presence of …?

A

Hydrogen peroxide

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10
Q

After filter paper rubbed over stain…

What is the process of LMG

A

Reduced leuchomalactive green added to hydrogen peroxide
Oxidised LMG
Colour change to blue/green

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11
Q

Kastle Meyer test procedure?

A

Reduced phenolphthalein, added to H2O2 oxidises it if positive reaction
Colour change to red-pink

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12
Q

Process of luminal preliminary testing?

A

Luminol = 3-aminophthalhydrazide
Luminol + h2o2 -> 3-aminophthalate
Light producing reaction- chemiluminescence

So spray luminal and h2o2 on region

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13
Q

Why is luminol useful?

A

Shows hidden crime scene- might not have seen blood
Luminol helps find trace evidence- Locard’s principle
Blood will show even if someone has mopped up
Can lead to more evidence

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14
Q

What is the problem with luminol?

A

It can destroy other evidence like finger prints and footprints
Bleach and saliva can provide a false positive

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15
Q

What are the advantages for finding semen?

A

Semen can stay up till 5 days

Large amounts of DNA

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16
Q

What is the first thing to do when testing for semen?

A

Dampen blotting paper and apply it to stain area

17
Q

Microscopy of semen

A

Test with staining agent

Spermatozoa

18
Q

What does acid phosphatase do in the presence of semen?

A

Produces a purple colour
Degree of colour proportional to quantity of enzyme

But also small quantity is present in vaginal fluid

19
Q

What is p30

A

Prostate specific antigen
Semen specific
And male urine

20
Q

Disadvantages to testing semen?

A

Some seminal fluid can be sterile- no Sperm

21
Q

Preliminary testing for saliva

A

Dampen blotting paper and apply to stain area
Test with iodine
Iodine turns blue black in presence of starch
Salivary amylase breaks down starch- so no colour change should occur if saliva present

22
Q

An advantage to finding saliva?

A

Saliva may contain bacterial or check cells- can look for DNA

23
Q

What does blood pattern analysis do?

A

Examines shapes, distribution and location of blood stains to interpret the events that gave rise to the origin

24
Q

How can blood analysis give information on the sequence of events?

A

You can sometimes tell if there has been struggle and the location and position of the victim

25
Q

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

A

Stain patterns on suspects clothing and on victim/at scene

26
Q

What are the three types of blood patterns?

A

Passive
Transfer
Projected/Active

27
Q

What are passive patterns?

A 
Due to gravity
Drips/drops of blood
Pools
Clots
Shape of these are affected by target surface texture- smooth/rough
28
Q

What are transfer patterns?

A 
Wet bloody surface in contact with another surface produces a pattern
Contact
Smear
Wipe
Smudge
29
Q

What is projected blood?

A

Arterial spurt/gush- blood exiting at big pressure
Cast off stains- comes from weapon (e.g. Pattern in arch- bringing back hammer)
Impact- low, medium, high velocity e.g. Bullet spray
Can tell point of convergence- point of impact, where victim may have been lying, follow angles of blood patterns

30
Q

The case of Billie-Joe Jenkins

A

Step father accused of murdering her
He said he found her and helped
158 tiny drops of blood on his clothes- impact splatter
Stabbed with tent peg
But under debate has if he had lifted the body, there could have been an impact in pressure and then a fine spray- pulmonary interstitial emphysema

31
Q

What is the importance of blood grouping?

A

Large samples can be eliminated by quick inexpensive screening
Used to eliminate large numbers of people

32
Q

What are the immunological biological markers?

Antigens present on blood cells

A 
ABO
Rhesus
MNS
Kell
Duffy
Kim
33
Q

What are the immunological systems?

A

Protein variants
Groups
Elimination

34
Q

What are the protein biological markers?

A

ACE
ACP
Haemoglobin
PGM

35
Q

What antigens and antibodies are present in people with blood type A

A

A Antigens

Anti-B antibodies

Forensics (11 decks)

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