Blood Splatter. Lab Experiment.

Experiment One.

Aim: To investigate how the diameter of the blood stains vary with the height

Apparatus: Retort stand, dropper, metre rule, protractor, clipboard, paper, artificial blood (70ml hot water + 25 g flour + food colouring), newspaper.

Procedure
2. Attach an A4 paper onto the clipboard and place it on the floor.
3. Place the dropper loosely between the clamp on the retort stand 10 cm above the paper as shown. DO NOT SQUEEZE YET !
4. Slowly tighten the clamp to allow only ONE drop of blood to drip onto the paper below.
5. Measure and record the diameter of the blood stain in the table below. (Is one measurement of the diameter enough?)
6. Label the blood stain as “A10”.
7. Repeat Step 4 and 5 to obtain another blood stain on another spot of the paper and label it “B10”.
8. Repeat steps 3 to step 6 by adjusting the vertical distance for 30 cm, 60 cm, 100cm, 150 cm and label them appropriately.
9. Plot a graph of average diameter of blood stain, d against vertical distance, s using "Numbers".

Set-Ups

Vertical Distance of 10cm

Vertical Distance of 30cm

Vertical Distance of 60cm

Vertical Distance of 100cm

Vertical Distance of 150cm

RESULTS

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Experiment Two

Aim: Investigate how the shape of the blood stains vary with the angle of impact

Procedure:
1. Lay the floor with newspaper to prevent the blood from staining the floor.
2. Attach an A4 paper onto the clipboard andplace it on the floor.
3. Place the dropper loosely between the clamp on the retort stand least 100 cm above the paper as shown. DO NOT SQUEEZE YET !
4. Elevate the clipboard to 10° as shown.
5. Slowly tighten the clamp to allow only ONE drop of blood to drip onto the paper.
6. Measure and record the length, L and width, W of the blood stain in the table below.
7. Label the blood stain as “P10”.
8. Repeat Step 5 and 6 to obtain another blood stain on another spot of the paper and label it “Q10”
9. Repeat steps 4 to step 8 by adjusting the vertical distance for 30°, 50°, 70° and label them appropriately.

Blood Splatter

Blood splatter 1. 

Formed by drop dripping vertically on to surface. Smaller splatters are evenly distributed around the blood drop 

Blood splatter 2.

Formed by one drop of blood dripping from high ground. A greater distance from the surface also means that the velocity of the blood drop is higher than in Blood Splatter 1. 

Blood splatter 3.

This is formed by a right to left motion. This can be seen by the larger circle of blood at the right, indicated the initial point of impact. There is a trail of blood to the left of the main drop followed by a smaller circular area of blood.

Blood splatter 4.

Each drop has a large area of blood where it first hit the wall. This large area is then followed by a trail of blood dripping onto the floor. This probably shows that each one was splattered on individually, and not in a smooth continuous movement. Except for the area of the corner of the wall, where the drops there do not have a trail of blood below it. Whoever splattered the blood did it in one action. All this leads to a deliberate and intentional application of blood to the walls and not murder or anything like that. 

Name as many factors that affected the splatters

Velocity, angle of impact, height of impact, direction of impact, texture of surface of impact, amount of blood. 

Hypotheses

The greater the distance between the initial height and surface, the greater the diameter of blood splatter. 

The direction of action causing the blood splatter can be determined by resulting blood splatter. 

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Factors that affect blood splatters.


Surface Tension
The surface tension of blood is not overcome by gravity and air resistance. It is only broken when the blood hits a surface. Different textures of surfaces causes different shapes of blood drops to be made. A hard, smooth, nonporous surface such as clean glass or smooth tile, will create little if any spatter in contrast to a surface with a rough texture such as wood or concrete that can create a significant amount of spatter. Rough surfaces have protuberances that rupture the surface tension of the blood drop and produce spatter and irregularly shaped parent strains with spiny or serrated edges.

Viscosity 


Angle of Impact
When a droplet of blood strikes a horizontal surface at 90o it produces a circular stain. As this angle gets lower, the diameter of blood drop increases. This drop will be enlongated, not a circular stain.

Height of drop
The greater the height of drop, the greater the diameter. A straight drop will generally cause a circular stain, and the diameter of this would increase. Even when the drop is from an angle (as mentioned about, the drop will be englongated), the diameter will increase when there is an increase in height.

Chromatography

Flame Test

• Metals change the colour of a flame 
• Flame tests can identify the type and presence of a particular metel in a sample
• However, when there is more than one element in a metal, this technique is no longer suitable. This is shown in Fig. 7

Calcium - Red-Orange 

Copper - Green 

Lead - White/Blue

Potassium - Lilac/Pink

Sodium - Intense Yellow 

Fig.1 Original Colour of Flame

Fig.2 Calcium - Red-Orange

Fig. 2 Copper - Blue-Green

Fig.4 Pottasium - Lilac/Pink

Fig.5 Lead - White/Blue

Fig.6 Sodium - Intense Yellow

Fig. 7 Contaminated Calcium

Fig.7 Shows us that if there are more than one trace metals in a sample, this test is no longer suitable. The calcium has been contaminated by Copper, thus the flame turning blue-green instead of orange-red. 

Fingerprinting

• Fingerprints do not change over time and age
• Each individual has a unique print
• Prints are classified into three basic fingerprint patterns. (Arch, Loop and Whorl)

Arch 

Loop 

Whorl

We carried out 4 different methods to obtain our fingerprints. 

Glue
We applyed glue on our fingertips and allowed the glue to dry before removing the layer of dried glue. The glue dried with the pattern of my fingerprint imprinted on it. This showed a very clear imprint of my fingerprint. However because the glue was not totally dried when I removed it the print was torn in half :(

Superglue Fuming
We pressed our fingertips onto a clear piece of plastic which was then placed in a glue fuming chamber. The superglue sublimed and the vapours of glue condensed on the oil left behind by our fingers. This produced a clear white print on the clear plastic.

Dusting
We pressed our fingertips onto a clear plastic again. By scraping off lead scraps from a pencil and then using a brush to dust the print, the lead dust stuck onto the oil from our fingers. This produced a dark dust print. Then, we used clear tape to lift the dusted fingerprint off the plastic to preserve it.

Iodine
The iodine test involved us pressing our fingertips onto a piece of filter paper then putting it into a flask with iodine crystals in it. When the iodine crystals sublimed, the prints appeared on the filter paper.

These four methods can be used to discover and lift prints left behind in a place from when a person made contact with a surface.

After fingerprinting (inking) myself on the worksheet and observing them through a hand lens, I have observed  that my prints are mostly of a loop pattern. Specifically, a left slant loop. But the loops curve in different directions on different fingers. The prints on my left and right hands are not mirror images of each other.

Lesson 1.

Case of the Trash Monster.

What did Slylock observe to help him identify the trash monster?
Suspects: Racoon or bull.

- Bones were found in the trash.
- Bull is herbivore.
- Racoon eats both
The racoon did it.

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Moonwalking bear.
Okay so I didn't notice the moonwalking bear.
It wasn't obvious! He doesn't look like a bear, and people were moving around so I didn't notice it. Was too focused on the basketball the first time the video played and the other times were because yeah he really doesn't look like a bear!

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"Every contact leaves a trace.
The very basic concept of forensic science and investigation.

Virtual investigation.
Evidence:

- Break in followed by struggle.
- Victim was a philandering man. (Possible motive -> Crime of passion)
- Unknown blonde woman seen entering victim's house at 1pm and left at 2pm in a seemingly good mood.
- Feisty redhead who has been seen together with victim before entered house at 4pm, leaving at 4:15pm.
- Unknown man seen loitering outside victim's house at 10:15pm.
- Lock on back door forced open by a tool. (Place of entry)
- Footsteps imprinted on mud near back door.
- Tool marks on broken lock.
- Paint chips on the ground at back door is collected.

- Living room (Place of struggle)
- Love/Hate letter found in living room.

- Hallway (Place of murder)

Footprints:
Right foot of a men's size 11 "Doc Martin" boot.
The heel is worn at the back, suggesting that the suspect drags his feet.

Toolmarks:
The first is a "compression" mark, where the tool made a slight indentation in the wood.
The second is a sliding impression in the metal surrounding the lock.
Suggests that a crowbar or similar tool was used.

Paintchips:
Can be compared to other traces of paint chips found on tool/suspect.

Love/Hate letter:
A guy was cheating on the person who wrote the letter and she was very angry.
Threats were mentioned in the letter.
Paper used was unique. Hand-made by people in third world countries sold in a shop called "We are the World."