Chromatography and Flame tests

Today we did chromatography. The theory was easier than expected, because we only have to cut out different letters to test whether they are written by the same pens. The results were not really good, though, as the traces are rather faint and they all look the same.
For the flame tests, we learned about how when different trace elements are burnt, different coloured light is emitted. The fires are really pretty, especially the copper (green), potassium (lilac) and an unknown element with white that has streaks of red. However, one bad thing is me and my partner took all videos and no photos :( what are we going to do for the camera album??

Finger Print

Fingerprint - oil, sweat and amino acids.
Fingerprints are unique, even for twins. - why?
Are DNA fingerprinting for twins the same or different? why?
What is DNA fingerprinting?
Fingerprints do not change with age.
Fingerprints can be burnt off by acid. Ouch.
Fingerprint classification system: whorls, arches, loops, etc.
Latent prints can be found on porous and non-absorbent materials. --> how is it going to affect the quality of the fingerprint.
Porous materials - iodine fuming, fluorescent and UV ray
Non-absorbent - Superglue fuming, powder dusting, silver nitrate - why the different methods.

Powder dusting:
-use the colour that contrasts the best with the background.
-black (charcoal) and gray (aluminium powder) usually sufficient
-used for hard and non-absorbent surfaces; powders will stick to the oil residues left on fingerprint
Magnetic powder dusting:
-magnetic sensitive powder spread with the use of magnet; lessen the risk of damaging the sample as there is no actual contact between the brush and the fingerprint.

Why twins have different fingerprints:


Bring camera and macbook for tomorrow!! Camera used to photograph iodine developed fingerprint.

Dumping trash

Suspect:
bull - wearing fashionable clothes, big-sized; herbivorous
raccoon - wearing clothes that do not fit-poor? small sized; omnivorous

Trash:
fishbones
banana peels, etc

Final verdict:
Raccoon is an omnivore, therefore he would be the suspect who dumps trash like fishbones that he ate.

every contact leaves a trace: physical evidence.

with contact between 2 items, there will be an exchange: forensic evidence. --> Locard's exchange principle

Awareness Test

I counted 13 passes.

I got it correct but I did not see the bear. I learn from this activity that when we focus on something, we would actually be able to block out other things very effectively. Therefore, when we are preoccupied, our awareness will reduce drastically. This is very important for observations because maybe when we investigate, we focus too much on looking for a particular thing that we miss out other things. 

Notes for the case study:

Suspects:

1. blonde, at the house around 1pm, in very good mood, never seen before.

2, redhead, at the house around 4pm, in very bad mood, seen before.

3, man, at house around 10-11pm, pacing in front of the house.

Place of struggle:

Living room: spilled wine, overturned armchair, broken glass pane in window, fallen lamp with the lamp cover fallen off.

Fibre piece found on armchair: shirt. 50% wool and 50% polyester. black, sweater. 

Print found on the murdering weapon: not someone with a criminal record. Patrick Murray, twice convict's prints were found in the room. 

hair strands found: two long and blonde, but of different shades; one bleached. two shorter, brown. one shorter, very red, belongs to a woman. 

Letter found: very jealous woman. the woman writes the letter on paper made by third world country people. 

Place of entry:

Lock forced open: tool to break open the door is a crowbar.

Suspect: Mrs Smith: detailed description of the man. 

Evidences:

1. foot print

2. paint

3. tool mark

4, physical "crime" tool

5, blood - splatter, stain, analysis

6, fibre

7, hair

8, document - handwriting, paper, etc

9, time of death (TOD)

10, Wound

11, DNA fingerprints

12, computer composites-suspect identification

13, glass 

Field:

Forensic scientist

-morphology- study of structure without taking into consideration the function

-pathologist-study of diseases

-coroner-an officer who investigates by inquest any death caused by unnatural causes