Que pasa guys,
In the past few blogs I have talked about various aspects of the forensic side to my course, the crime scene village, ESDA and Fingerprint techniques. This week I will finish off my forensic facts series blogs with talking about another really interesting part of the ‘Criminalistics’ module in the first year of study here at Glamorgan university and that is bloodstain evidence.
We spend a number of sessions in the first year, both practical and theory, looking at bloodstain evidence and the various spatter patterns produced from different experiments. There are many names used to describe the spots formed when a pool of blood is struck and it is difficult to know quite what to call them no matter how obvious they may look. SOCOs, forensic scientists and students alike use words such as spots, splashes, blots, splodges, blobs, splatters and spatters. These words are the correct terms to be used in forensic analysis of blood patterns; even though they sound like something we would have said when we were five when describing our paintings or something like that!
We look at various different experiments as dripping blood from a syringe at different heights to observe what patterns are formed and determine if there is a minimum height needed to produce a spatter.
We stepped in to a pool of blood using a different impact force each time, from a tap to a stomp, and recorded the different patterns.
Another experiment we conducted was looking at the angle of impact, where we transferred a few spots of blood from nose height on to paper from angles 0-90 degrees and then carrying out a nice calculation (not so much) involving the width and length of the blood splodge and sinɵ (the angle being calculated, i.e. 30 for 30 degrees). If you watch Dexter, you can see this experiment on the wall of his office in the series, it’s pretty interesting.
The projected blood experiment that we did was pretty cool, we were looking at patterns caused from blood squirted from a syringe. These were to attempt to recreate splashes that would be caused by a severed artery (frequently called arterial spurting patterns). Check out the pictures below. These splashes impact a surface with greater force and so appear more like streaks facing away from the central pool of blood, with a few drops flying further. We then had a go at some contact patterns in which we would dip some tools in to blood and press them on to paper to see how they would appear, finally developing a sequence of events in which we would include items of clothing and shoes as well to see if was easy to interpret what mark was made first.
Creating cast off splashes was awesome! The crime room just off of the main lab has walls covered in plastic and for this experiment we were determining the direction in which the spatters travel. We dipped a crowbar, hammer, as well as various other items and literally just swung our arms all over the place and kept a sheet of paper, drawing arrows on to show the directions – at this point our lab coats were covered in splashes too, it looked like some kind of Halloween costume haha!
The most fun, and in some ways menacing, part of the blood experiments was hitting a bloody surface. For this there was a sponge in the shape of a head soaked in blood. Can you see where this is going? Indeed; we used, once again, various ‘weapons’ to strike this sponge head on a surface enclosed in a box-type area and see what patterns were developed from this blunt-force trauma! Can’t help but feel like something off of Dexter throughout these experiments!
So, yeah we look at a lot of blood spatter patterns and get to play with a lot of blood, whilst learning at the same time – great fun! Definitely worth a research if you guys are interested. Hope you like the pictures. Get in touch if you have any questions.
Until next time.