Bloodsplatter Pattern Analysis

Question 1

What are the 5 factors that affect the appearance of a bloodstain?

Answer 1

1. The velocity at which it was travelling
2. Distance travelled
3. The amount of blood
4. The angle of impact
5. Type of target onto which it lands

Question 2

What are the 9 things that a bloodstain can tell us?

Answer 2

1. Number of blows struck during an accident
2. Number of perpetrators
3. Sequencing of events
4. Positioning of persons within a scene
5. Directionality of droplets
6. Angle of impact
7. Objects used (weapons)
8. Force involved in the bloodshed and the direction the force was applied
9. Evidence of clean up

Question 3

What is bloodstain pattern analysis?

Answer 3

• examination of the size, shape and distribution of bloodstains and bloodstain patterns
• draws on the scientific principles of biology, chemistry, mathematics and physics
• based on the premise that all bloodstain patterns are characteristics of the forces that created them

Question 4

What shape will a blood droplet take in the air?

Answer 4

Sphere

Question 5

What is a bloodstain?

Answer 5

The transfer of when liquid comes into contact wth a surface or when a moist or wet surface comes into contact with dried blood

Question 6

What are some locations of bloodstains?

Answer 6

• scene
• victim (body/clothing)
• offender (body/clothing)
• weapon
• vehicle
• furniture
• “clean up”: under rugs, linoleum, seat cushions

Question 7

What is blood comprised of?

Answer 7

• 55% plasma: 91% water, 8% proteins, 1% organic acids/salts

- 45% proteins: 99% RBCs, 1% WBCs, 1% platelets

Question 8

What are the functions of blood?

Answer 8

• transport
• protection
• regulation

Question 9

How much of the body weight does blood account for?

Answer 9

8%

Question 10

How much blood do males and females have?

Answer 10

Males: 5-6L
Females: 4-5L

Question 11

How much blood loss will render someone unconscious?

Answer 11

1.5L

Question 12

How much blood loss will result in death?

Answer 12

40%

Question 13

What are the presumptive tests for identifying blood?

Answer 13

• hemastix
• luminol test
• phenolphthalein test

Question 14

What are the confirmatory blood tests?

Answer 14

• ABA card hematrace
• Takayama test
• RSID test for human blood

Question 15

Where is DNA present in blood?

Answer 15

Only in WBCs because RBCs lack nuclei and ribosomes

Question 16

Hemastix test

Answer 16

• presumptive test
• looks for peroxide-like activity of haemoglobin in RBCs
• will not detect the difference between animal and human blood
• false positives: beetroot, rust, horseradish, copper, cabbage, animal saliva, past expiry date

Question 17

Luminol test

Answer 17

• presumptive test
• luminol reacts with haematin and produces a luminescence
• false positives have been observed with the presence of copper salts (on locks, door handles)

Question 18

Phenolphthalein test

Answer 18

• presumptive test
• presence of blood detected based upon a peroxidase reaction of haemoglobin which produces a pink colour
• false positives: saliva, pus, malt extract, vegetable extracts, the salts of certain heavy metals

Question 19

ABA card hematrace

Answer 19

• confirmatory test
• immunochromatographic test for detecting the presence of human haemoglobin
• intended for use on stains that have tested positive using the phenolphthalein test

Question 20

Takayama test

Answer 20

• confirmatory test
• hemochromogen crystals form when mixed with blood
• crystals are observable under a microscope and look like salmon-pink rhomboid crystals

Question 21

RSID test for human blood

Answer 21

• confirmatory test

- specialised antibodies detect the presence of human Glycophorin A found in RBC membranes

Question 22

What are the 4 broad categories of blood stains?

Answer 22

1. Passive
2. Transferred
3. Projected
4. Altered

Question 23

What is a satellite stain?

Answer 23

A small stain that originated during the formation of the parent stain as a result of blood impacting a surface

Question 24

The more ……. the angle of impact, the …….. elongated the teardrop

Answer 24

Accute, more

Question 25

What do passive bloodstains include?

Answer 25

- flows, drops and pools | - usually results from gravity

Question 26

Flows

Answer 26

Accumulation of a volume of blood with regular margins that has been moved across a surfaces as a result of gravity or the countour of the surface

Question 27

Drops

Answer 27

Result in distinctive patterns diagnostic of the event.

Question 28

Pools

Answer 28

An irregular stain caused by deposition;contact by a large source of liquid blood

Question 29

When a drop strikes a surface perpendicular, the drop will be......

Answer 29

Circular

Question 30

What are the types of transfer bloodstains?

Answer 30

- swipes, wipes and transfers | - results from objects coming in contact with existing bloodstains

Question 31

How are bloodstains documented?

Answer 31

1. Written report: directionality and bloodstain classification 2. Photography: photos of the scene before anything is touched or moved 3. SketcheS and diagrams: position of the body in relation to fixed and significant objects in the scene

Question 32

Swipe

Answer 32

Pattern resulting from the transfer of blood from a blood-bearing surface onto another surface

Question 33

Wipe

Answer 33

Pattern resulting from an object moving through a preesistono wet bloodstain

Question 34

Transfer

Answer 34

A contact bloodstain created when a wet, bloody surface contacts a second surface as a result of compression or lateral movement. A recognisable mirror image (or portion) or the original surface may be transferred on to the second surface

Question 35

What does the projected category contain?

Answer 35

- impacted, expirated, cast off and arterial

Question 36

Impact

Answer 36

Results from blood projecting through the air and are usually seen as a splatter, but may also include gushes, splashes and arterial spurts

Question 37

Expirated

Answer 37

Blood from and internal injury mixing with air from the lungs being expelled through the nose, mouth or an injury to the airways or lungs (coughing) Seen as a fine mist, small droplets of blood

Question 38

Cast off

Answer 38

An object swung in an arc flings blood onto nearby surfaces

Question 39

Arterial

Answer 39

The spurt of blood released when a major artery is severed, often forms an arching pattern which occurs every time the heart pumps

Question 40

What does the altered category include?

Answer 40

- Clotted, dilute, diffuse, insects, voids and sequence | - includes any other type of bloodstain that doesn’t fit into the first 3 categories

Question 41

Clotted

Answer 41

A gelatinous mass formed by the collection of blood cells in fibrin

Question 42

Diluted

Answer 42

Whole blood subject to volume alteration due to fluid addition/mix, I.e. in a sink

Question 43

Diffuse

Answer 43

Movement of blood from and area of higher to lower concentration, I.e. material absorbing blood

Question 44

Insect

Answer 44

Bloodstain resulting from insect activity

Question 45

Voids

Answer 45

Absence of blood staining in an otherwise continuous pattern

Question 46

Sequence

Answer 46

2 or more splatter types co-mingled or time sequenced