CSI: Blood Splatter Part 2

Here is our group's video!

CSI: Blood Splatter Experiment Results

We did an experiment whereby we had to drop drops of fake blood from a retort stand at different angles and heights. Here is the results for the different heights dropped:


Distance from paper / cm          Average diameter/cm      
10                                                     0.85
30                                                     1.1
60                                                     1.25
100                                                   1.35
150                                                   1.4

Graph of above results

Here are the results for the angle of elevation:


Angle of elevation / °         Average length/cm
70                                          2.4
50                                          1.9
30                                          1.55
10                                          1.35


Angle of elevation / °           Average width/cm
70                                         0.75
50                                         1.15
30                                         1.25
10                                         1.6

CSI Blood Splatter Practical

Blood Splatter Pattern from a Laboratory Experiment by Mr Leong TK & Chua HL

Questions:

1. What is shape of blood splatter?
2. Describe any other characteristic of the splatter.
3. What are the factors that affect the shape of the blood splatter? Name as many as possible.
4. Generate some hypotheses from the blood splatter patterns observed above.

1. The shape of the blood splatter is circular with jagged edges, but becomes more and more elongated as the angle of elevation increases.

2. The blood drop is concentrated in the middle and has an irregular, less concentrated fringe. This is because the blood spreads and divides into 2 distinct layers.

3. Height, velocity, angle at which it was dropped, direction, nature of instrument which caused the blood splatter

4. The greater the angle of elevation, the more elongated the blood splatter.

CSI: Flame Tests and Chromatography

Chromatography:

Waiting for pen ink to come off into the ethanol

Running the chromatography! (pen ink)

Chromatography strips at the end

Flame Tests:

Original colour of flame

Potassium nitrate

Magnesium

Lead II nitrate

Sodium nitrate

Calcium chloride

Copper II nitrate

CSI: Fingerprinting

NOTES - THEORY


Evolution:
Informant -> ID: photography, measurements, branding -> Fingerprinting (extraction) -> DNA fingerprinting


- French police Bertillon identified criminals through measurements:

• crown (circumference of skull)
• length of arm
• armspan

- Fingerprints quickly replaced this system.

• Latent - can be made visible with special techniques
• Paper
• Plastic

- Iodine vapour; fades and must be photograph
- Super glue fumes
- Dusting powder

~~~

PRACTICAL PART 1

We did a lab practical to test the different methods of taking one's fingerprints. Unfortunately, I did not bring a camera...

Wood Glue Method

- Where are the pores found? Are they regularly spaced out?

- Are the lines of your print equally spaced throughout?

The lines on the fingerprint are not exactly equally spaced throughout, but they are of more or less the same distance. It was not easy to see the pores, because the fingerprint specimen was ruined in the process of trying to scrape the glue of our finger! (In our haste to finish the experiment, we had neglected to let the glue dry completely, and thus the print tore in 2 when we tried to take the semi-solidified glue print off our finger!)

Superglue Fuming method

- If the contrast of the white print against the black background is still too faint for a good detailed photograph to be captured, what could be done to enhance the fingerprint?

This is the answer I got from a website:

"This is the technique of dusting. Different colored dusts may be brushed onto the image of the fingerprint, and they will cling to the sticky white chemical from which it is formed, effectively changing its color."

http://www.ccs.neu.edu/home/feneric/cyanoacrylate.html

Iodine Fuming Method

 - What are the possible substances that may be used to render the prints more permanent?

- Why does the print disappear?

- Possible substances: Print is sprayed with a 1% solution of starch in water, which will turn the print blue and make it last from several weeks to several months. 

http://www.bxscience.edu/publications/forensics/articles/fingerprinting/f-fing03.htm

However, the most common is to take a picture of the print at its highest colour intensity before it fades. This is usually sufficient enough to determine the patterns of the fingerprint. The print disappears due to the fact that iodine sublimes (i.e. changes from solid to gas)


Power Dusting Method
Although my group members and I created a huge pile of lead shavings, we could either see only half of the OUTLINE of the print or nothing at all!


- What is magnetic powder dusting and how does it work?
A fine magnetic powder is held by a magnetic applicator, which may then be gently moved across the fingerprint. As no bristles touch the surface, this often damages the print less than other methods of developing the print. 
http://en.wikipedia.org/wiki/Fingerprint_powder

~~~

PRACTICAL PART 2

Classification and Identification of Fingerprints

My own fingerprint database (it appears back to front because I didn't have a camera and had to take it with photobooth!)

The prints aren't very clear as I pressed my finger in the ink rather gently, but on the paper, they appear much clearer.

Class data:
Finger Pattern        213 Class Data/%
arches                   17.86
whorls                   28.57
loops                     53.57

According to the fingerprint database in the US:

• 60-65% are classified as loops
• 30 – 35% are classified as whorls
• 5% are classified as arches

The general trend is the same, with loops being the most common, followed by whorls and then arches. However, because we have a much smaller sample size, there seems to be a considerably larger number of arches as compared to the US data.

Questions:

- Are the patterns of your thumb print for the right and left hand the same?

- Are the patterns of the all of the fingers same, similar or different?

The patterns of my thumb print for both hands are different: my left print is that of a plain whorl while my right print is that of a right slant loop. The patterns of all the fingerprints seem to follow that of the thumb on each hand i.e. the other 4 fingers of the left hand are classic whorls while the other 4 fingers on the right hand are right slant loops.

CSI: 1st lesson and thoughts

Case of the Trash Tosser

Suspect of crime: Raccoon

Raccoons are omnivores, and Slylock fox found evidence of vegetables and fish bones. The bull is herbivorous, and so is not likely to be the suspect.

Awareness Test

How many tosses did you count?
Did you get it correct?

I counted 13 tosses, which was correct. However, I definitely did not notice the moon walking bear! This means that I can actually stay focused on something without being distracted by other things, which may prove useful in helping me stay focused on tasks that I am doing. I have heard of something similar, but a gorilla walked by instead of the bear. The bear was cleverly dressed in black, which was similar to what the black team was wearing and hence not very noticeable.

Crime Scene Investigation

• List the physical evidence that you have found on the various crime scenes.
• What are the field of studies that were brought up in the case study?
• What qualities should you possess or cultivate to be a good investigator?

Clues collected


1.     Footwear impressions allow you to match the impression with actual footwear owned by suspect.
2.     Toolmark impressions allow you to match the impression with actual tools owned by suspect.
3.     Paint examination allows you to match a tool to the crime scene, when the tool is found.
4.     Computer composites can help with suspect identification.
5.     Hair analysis enables comparisons with the suspect's hair or with hair found on the suspect's clothing
6.     Document analysis can verify the authenticity of a document and who the author is.
7.     Fingerprint analysis is still the predominant means of establishing positive identification.
8.     Blood stain pattern analysis tells you how a crime was committed.
9.     Blood analysis lets you identify a victim or a suspect, because DNA is unique to each individual.
10.  Wound analysis can help with identifying the murder weapon.
11.  Pathology allows you to establish time of death and compare with suspect's schedule.
12.  Fiber analysis rests on the principle that whenever two individuals are in contact, materials (dust, paint, cloth etc.) are exchanged at a microscopic level.   

Evidence

1.     Foot print

2.     Paint

3.     Tool work

4.     Physical “crime tool”

5.     Blood/splatter/stain

6.      Fiber

7.     Wood

8.     Hair

9.     Document-handwriting

10.   Time of death (TOD)

11.   DNA fingerprint

12.   Wound

Field

1.     Forensic Scientist

2.     Morphology

3.     Pathologist

Qualities of a good investigator


A good investigator has to be very observant and sensitive to details, in order to pick up clues easily. She must also be patient because sometimes, it takes a long time before one can form an accurate picture  of the crime as people may give false witnesses.