Blood Identification

Lab Partners: Sheena Lee and Teo Kar Leng

Why do Test 3 last?

Most difficult to do (many complex procedures)

Test 2 is most commonly done (easiest to carry out)

Test 1:

Aim- To determine whether a stain is blood.

Results- 

Sample	Prediction and reason for prediction before H2O2 test	Observation (during the test)	Result (Tested +ve or –ve for catalase)
1	Yes. It’s red in colour and very thick.	No bubbles	-ve
2	No. Looks and smells like salsa sauce.	No bubbles	-ve
3	No. Looks and smells like fruit juice	No bubbles	-ve
4	Red in colour, looks and smells like blood	Bubbles (instant)	+ve
5	No, because it’s dark purple in colour	Bubbles (instant). But stopped after awhile.	+ve
6	No, because there’s specks of the sample in solution	Little bubbles formed at the bottom after awhile.	+ve

Blood Splatter Experiments (Graphs)

Experiment 1:

Experiment 2:

Blood Splatter

Blood Splatters taken from rambio2011.wikispaces.com :

Blood Splatter 1

Blood Splatter 2

Blood Splatter 3

Blood Splatter 4

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

What is the shape of the blood splatter?

Round or oval, with different lengths and widths.

Describe any other characteristic of splatter.

The blood splatter is darker in the middle (more concentrated?) and are either irregularly-shaped or elliptical. As the blood is dropped from a greater height, the blood splatter would be more concentrated in the middle. The greater the angle in which the blood is dropped, the greater the length of the blood splatter.

What are the factors that affect the shape of the blood splatter? Name as many as possible.

1) Angle at which blood is dropped.

2) Height at which blood is dropped.

3) Force applied on blood splatter.

4) Amount of blood.

5) Surface which blood is dropped on. 

Generate some hypotheses from the blood splatter patterns observed above.

1) The greater the height at which the blood is dropped, the more concentrated the blood splatter is at the middle. (more blood satellite splatter)

2) The greater the angle of impact of the blood splatter, the greater the length of the blood splatter. (more spread out)

EXPERIMENT 1:

Aim:

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

Results:

Height (cm)	Diameter – A (cm)	Diameter – B (cm)	Average Diameter (cm)
10	1.1	1.0	1.05
30	1.2	1.2	1.20
60	1.3	1.3	1.30
100	1.3	1.4	1.35
150	1.4	1.7	1.55

EXPERIMENT 2:

Aim: 

Investigate how the shape of the blood stains vary with the angle of impact.

Results:

Angle of Impact (degrees)	Width – P (cm)	Length – P (cm)	Width  – Q (cm)	Length – Q (cm)	Average Width (cm)	Average Length (cm)
10	1.4	1.4	1.3	1.4	1.35	1.40
30	1.3	1.5	1.3	1.5	1.30	1.50
50	1.3	1.7	1.3	1.8	1.30	1.75
70	0.7	2.4	0.7	2.5	0.70	2.45

Explanation (from rambio2011.wikispaces.com):

There is arelationship between the length and width of a bloodstain and the angle at which the droplet impacts on a surface. Theangle of impact on a flat surface can be calculated by measuring the length and width of a stain. The angle of impact is the acute angle that is formed between the direction of the blood drop and the surface it strikes. This is an important measure because it is used to determine the area of convergence and the area of origin.

When a droplet of blood impacts a surface at 90°, the bloodstain will be circular. The stain will be more elliptical when the angle of impact increases.

Identification of Fingerprints

Three Fingerprint patterns are Whorl, Arch and Loop. 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.

Mine's 'Loops'. (:

Fingerprint Database of 210 and 213 Fingerprints (from wikispaces website)

	210	2	arches
	210	1	loops
	210	4	loops
	210	5	loops
	210	6	loops
	210	6	loops
	210	7	loops
	210	8	loops
	210	9	loops
	210	10	loops
	210	13	loops
	210	15	loops
	210	16	loops
	210	19	loops
	210	25	loops
	210	25	loops
	210	26	loops
	210	29	loops
	210	30	loops
	210	3	whorls
	210	10	whorls
	210	11	whorls
	210	12	whorls
	210	17	whorls
	210	18	whorls
	210	20	whorls
	210	21	whorls
	210	23	whorls
	210	24	whorls
	210	27	whorls
	210	28	whorls
	210	31	whorls
	210	32	whorls
	213	4	arches
	213	14	arches
	213	19	arches
	213	23	arches
	213	32	arches
	213	1	loops
	213	3	loops
	213	6	loops
	213	10	loops
	213	15	loops
	213	18	loops
	213	20	loops
	213	22	loops
	213	24	loops
	213	25	loops
	213	26	loops
	213	28	loops
	213	29	loops
	213	30	loops
	213	33	loops
	213	2	whorls
	213	7	whorls
	213	13	whorls
	213	16	whorls
	213	17	whorls
	213	21	whorls
	213	27	whorls
	213	31	whorls

Raw Data from 210:

No. of 'Arches' - 1

No. of 'Loops' - 18

No. of 'Whorls' - 14

Total number of submissions is 33 for 210, although there were only supposed to be 31. :/ Oh well.

Raw Data from 213:

No. of 'Arches' - 5 

No. of 'Loops' - 15 

No. of 'Whorls' - 8

Graphs which I plotted:

The data plotted resembles that of the American database. (:


Graphs from rambio2011.wikispaces.com: