Blood Splatter

http://science.howstuffworks.com/bloodstain-pattern-analysis3.htm (quite an informative site about Blood Splatter)

Blood Splatter 1

Blood Splatter 1

• "blob", fairly circular

• thick and concentrated at one spot with tiny droplets splattered around it

Blood Splatter 2

Blood Splatter 2

• multiple drips OR someone was slammed and then dragged and bounced

• one main contact point (guess)

• splattered evenly outwards (referring to the tiny droplets around the main blood splatter)

Blood Splatter 3

Blood Splatter 3

• Multiple drips from different heights

• all are fairly circular

Blood Splatter 4

Blood Splatter 4

• Narrow oval shaped

• Probably quite thick as much of the blood dripped down the surface

Factors affecting shape of blood splatter:

• Height of where the blood originated from to the surface of blood splatter

• Angle of blood splatter

• Size/depth of wound, affecting the amount of blood splattered

• Type of contact with surface (e.g. physical contact - person slammed against surface, non-physical - blood was dripped)

Part 1

Experiment 1 (Height):

Set-up:

Results (flipped):

Height	Diameter of blood Stain/cm
	A	B	Avg
10	0.8	0.8	0.8
30	1.0	1.1	1.05
60	1.1	1.2	1.15
100	1.3	1.3	1.3
150	1.2	1.4	1.3

Experiment 2 (angle):

Results:

Angle of elevation / °	LP / mm	LQ / mm	LAve / mm	WP / mm	WQ / mm	WAve / mm	i/°
10	13.0	15.0	14.0	13.0	14.0	13.5	83.0
30	15.0	16.0	15.5	13.0	13.0	13.0	63.3
50	19.0	19.0	19.0	11.0	11.0	11.0	39.3
70	28.0	26.0	27.0	9.0	9.0	9.0	21.6

Part 2

My bench's "artwork":

(huimin, xinyi, wanying and I)

The blood is dripping downwards, so it can be deduced that the blood splatter was made on the wall and not on the floor. AnYee's group guessed that the big slash in the middle was from the top down as the top has more blood than the bottom. However, we actually did it from the bottom up! The reason why the top has so much blood is because we purposely squirted a lot more blood at the end. The small slashes along the sides of the main slash were made with high velocity as the slashes are very thin and taper towards the ends, eventually separating into slanted droplets. They were also made at an angle as the individual droplets are oval shaped (we learnt this in Experiment 2 above). The handprint was supposed to be made by the murderer as the hand seems to have bled a lot in the centre of the palm and murderers usually do not get injured:)