Lesson 7

For this lab lesson, my partners were Joyce, Chin Ying and Min Yi. The pictures say it all!

 Experimenting, experimenting...

 And more experimenting!

 One of the many set-ups we used, and some of our raw data.

Creating our very own 'crime scene' in the toilets, then cleaning up the mess afterwards! 

On the left is our group's work, which has an extremely structured storyline.

 Some of the other groups' (art)work.

Whee! Our final product. I shall refrain from putting up the whole sequence of how the murder was committed, since another group has to solve it first! 

The pink bits are supposed to be the words 'Majulah Singapura', for your information.

My group has also plotted our data into graphs to observe the trends and relationships, as below.

The whole class's graphs are on a single spreadsheet, at the following link:                     https://spreadsheets.google.com/spreadsheet/ccc?key=0AmiXOZN9ezMsdEMyRjYtbFJLM0pJQ3VBb1hiNmViZVE&hl=en_US#gid=0

Lesson 5 and 6

Lesson 5 was a briefing on the CSI PT (group), along with a video (edited from a Japanese movie) showing a CSI case. I missed quite a bit of this lesson, only managing to catch the end of the video, due to a lengthy MSP phototaking. :(

In lesson 6, we were introduced to the idea of blood spatters! Using the shape and size of blood spatters, we can actually know more about the crime committed, for example, what kind of weapon was used and how the victim might have been injured/murdered. Another video was shown to better illustrate the workings of analysing blood splatters, and how it can be quite misleading at times.

A lesson learnt from this video is: do not jump to conclusions! Make unbiased observations first before inferrences. Keep an open mind at all times. I think this is really important for scientists and in this case, the CSI people, because the answers to a case might not be as expected.

Next up in lesson 7 would be hands-on experiments on blood splatters, investigating how the distance between the blood drop and the surface, as well as the latter's angle of elevation, affects the shape and size of blood splatters.

Chromatography Rf Values

First digit '9'

Solvent front: 12.3 cm
Blue: 11.1 cm
Pink: 9.9 cm

Rf Values
Blue: 0.902
Pink: 0.805

Second digit '0'

Solvent front: 11.7 cm
Blue: 9.1 cm
Pink: 8.3 cm

Rf Values
Blue: 0.778
Pink: 0.709

Third digit '0'

Solvent front: 11.5 cm
Blue: 9.1 cm
Pink: 7.4 cm

Rf Values
Blue: 0.791
Pink: 0.643

Fourth digit '0'

Solvent front: 11.1 cm
Blue: 7.0 cm
Pink: 4.2 cm

Rf Values
Blue: 0.631
Pink: 0.378

Fifth digit '0' (the weird one)

Solvent: 12.1 cm
Blue: 7.1 cm
Pink: 5.9 cm

Rf Values
Blue: 0.587
Pink: 0.488

Lesson 3 and 4

Lesson 3 was spent on reading up on rambio about the various colours emmitted when ceratin metals are heated over the flame. This technique is known as flame test.

Today (lesson 4), we carried out a chromatography experiment, as well as a very fun hands-on flame test! First, we had to identify forgery in a cheque using chromatography. The first step was to cut up the written numbers, and then soak them in (a bit of) ethanol. Next, a few drops of the different ink solutions were dripped onto separate chromatography strips, which were then dipped in water. Pictures below to illustrate the experiment. 

Cutting up the cheque

Ethanol used

Soaking the paper with ink in ethanol

The chromatography set-up

Chromatography strips at end of experiment

Second is the flame test! Below are the really cool pictures of the flames when the different metals were held over them. 

Potassium nitrate

Barium nitrate

Calcium chloride

Sodium nitrate

Copper (II) nitrate

Magnesium

Lead (II) nitrate

Lesson 2

Fingerprinting

Iodine Fuming Method

Processing...

The product! (It is quite faint though.)

Cyanoacrylate (Superglue) Fuming Method

The first try, which turned out blurred because Chin Ying and I unthinkingly went to plaster the strip against the science lab door while trying to rub it down with ethanol!

Much clearer this time! The top two are my right thumb and index finger respectively. The big fat blob at the bottom belongs to Chin Ying.

Ridges and Pores Activity (using white glue to make an impression of the fingerprint)

Both pictures are impressions of my left thumb. Taken with my phone's camera! I had a hard time adjusting the angle of my phone so that it can "see" down the microscope. About the coolest thing I have seen thus far...

Powder Dusting Method

Powder dusting really takes a bit of skill. My right thumb, positioned on the left. It is quite okay-done, except for an odd little air bubble at the side.

Creating a Database

Lesson 1

Slylock Fox’s Investigation

Culprit: either the bull or the raccoon.

It is the raccoon, because there are bones, banana skin and remnants of vegetables found in the litter. This points to the animal being an omnivore. Since the raccoon is an omnivore and the bull is a herbivore, it must have been the raccoon. 

Awareness Test

I counted only 12 passes, but that was probably because I did not look up in time at the start. However, like many others I failed to see the moonwalking bear. This means that while concentrating on counting the number of passes, I could not divert my attention to other happenings.

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.