Types of Splatter<\/h2>\n
For those of you who like your science seasoned, let\u2019s talk about patterns first.<\/p>\n Bloodstains come in three main types. They are classified as passive, transfer or impact.<\/p>\n Passive stains are those that fall with low velocity such as a single drop of blood. A drop falling from a 90\u00b0 angle is most likely to form a sphere, as seen in the left hand picture in image 1. Pooling is another passive form of bloodstain, however a pool can cover more useful blood patterns. Passive bloodstains are blood leaking from the body and responding to gravity (\u20187 Things, 2015).<\/p>\n Transfers marks include hand and footprints, and also drag marks. They are best used to help read how objects have been moved around the scene (\u2018Blood Pattern Analysis\u2019).<\/p>\n These are the actual blood spatters, as seen in the picture on the right in image 1.The raindrop-shaped bloodstains help determine the location of the crime within the scene. These come from gunshots or arterial spurts. Another form of splatter is made as Cast-off:<\/strong> when the instrument used to wound is drawn back and blood flies off. In cast-off, the pattern forms in a line, either curved or straight, depending on the angle of the draw-back (\u2018Blood Pattern Analysis). If there is more than one swing, then a Crime Scene Investigator (CSI) \u00a0will see more than one line when reading the pattern.<\/p>\n The surface that the stain lands on can also affect the reading. If the surface is absorbent then the stain is less likely to form a helpful pattern. If the stain lands on vinyl wallpaper then the stain will look very like the pictures in image 1 (\u20187 Things\u2019, 2015).<\/p>\n A void happens when an object, such as a person, is in the way of the spray of blood and it leaves a blank area in the patterns in the room. It allows the investigators to see where people were during the incident (\u2018Principles\u2019, 2013).<\/p>\n <\/p>\n With blood splatters, the important point to remember is that that tail points away from the direction of flight, and that\u2019s where mathematics comes in.<\/p>\n Now on to the part I enjoy. Without mathematics, BPA would be based on the subjective viewpoint of the officer in charge. I agree that humans instinctively calculate how to jump or throw a ball (Peery, 2003). But by using mathematics, \u00a0it is possible to read the action in the room from the bloodstains and the voids and have evidence that stands up in court<\/strong>.<\/p>\n The shape of the bloodstain depends on \u00a0the angle of impact. As I said above, at a 90\u00b0 angle the bloodstain is likely to be a sphere.\u00a0 Once the angle is below 75\u00b0, then the pattern elongates into the classic teardrop shape( National Forensic Science Technology Center). The angle of impact is vital to learning where the droplet originated. This can be learned by dividing the width of the droplet by the length as shown in image 2, below.<\/p>\n By taking the inverse sin of the result, we get the angle of impact, as show in the formula below.<\/p>\n As I mentioned, the tail of the droplet is always away from the direction of travel. Once the angle of impact and direction of each droplet is determined, then the CSI can use this information to attach strings to the room. Where the strings cross is where the injury happened.\u00a0 If you are interested in this process here is a video showing stringing<\/strong>. https:\/\/www.youtube.com\/watch?v=vS6aMoczicA<\/a> from 1.51, but the earlier part shows how to do the calculations.<\/p>\n In 1895, Dr. Eduard Piotrowski of the University of Krak\u00f3w was the first to describe the usefulness of blood pattern analysis at a crime scene in his paper \u2018On the formation, form, direction and spreading of blood stains after blunt trauma to the head\u2019<\/em>. But BPA was not used in the US until the 1950s (Leverhulme, 2018).<\/p>\n The purpose of Forensic investigation is to have evidence-based convictions. Therefore, along with using personal experience to read blood patterns, it is vital to include mathematics to back up your evidence.<\/p>\n <\/p>\n Should you wish to know more, then check out the articles and books in the references.<\/p>\n \u20187 Things You Didn\u2019t Know About Blood Splatter Analysis\u2019. (2015, May 6). Forensics Colleges<\/em>. https:\/\/www.forensicscolleges.com\/blog\/resources\/7-things-about-blood-spatter-analysis<\/a><\/p>\n \u2018Blood Pattern Analysis\u2019. The Forensics Library<\/em>. https:\/\/aboutforensics.co.uk\/bloodstain-pattern-analysis\/<\/a><\/p>\n \u2018Principles of Bloodstain analysis\u2019. (2013) Forensic Science Simplified<\/em>. http:\/\/www.forensicsciencesimplified.org\/blood\/principles.html<\/a><\/p>\n Peery, N.R., (2003) Instincts: The Hidden Spirits That Drive You.<\/em> iUniverse, inc. https:\/\/books.google.co.uk\/books?id=4LgkOcUroiYC&pg=PT102&lpg=PT102&dq=instinctive+mathematics+of+throwing+a+ball&source=bl&ots=_IOBh5NtcT&sig=ACfU3U1V854No_dU4i9la-x8GsKHWfACng&hl=en&sa=X&ved=2ahUKEwjI55POv5j2AhUOY8AKHbEhCMwQ6AF6BAgXEAM#v=onepage&q=instinctive%20mathematics%20of%20throwing%20a%20ball&f=false<\/a><\/p>\n National Forensic Science Technology Center. A Simplified Guide to Bloodstain Pattern Analysis.<\/em> Bureau of Justice Assistance.\u00a0 http:\/\/www.forensicsciencesimplified.org\/blood\/BloodstainPatterns.pdf<\/a><\/p>\n Gomez, M. (2021, November 22). \u2018Solving Crimes with Math: Blood Pattern Analysis\u2019. +Plus Magazine: Living with Mathematics.<\/em> https:\/\/plus.maths.org\/content\/solving-crimes-maths<\/a><\/p>\n![\"showing](\"https:\/\/mozartcultures.com\/en\/wp-content\/uploads\/2022\/02\/BPA-www.forensicsciencesimplified.org_-300x122.png\")
Passive<\/h3>\n
Transfer<\/h3>\n
Impact<\/h3>\n
Landing Surface<\/h3>\n
Void<\/h3>\n
Mathematics<\/h2>\n
![\"Image](\"https:\/\/mozartcultures.com\/en\/wp-content\/uploads\/2022\/02\/calculating-the-angle-of-impact-300x134.png\")
![\"showing](\"https:\/\/mozartcultures.com\/en\/wp-content\/uploads\/2022\/02\/calculating-the-angle-of-impact2.png\")
History<\/h2>\n
Finally<\/h2>\n
![\"image](\"https:\/\/mozartcultures.com\/en\/wp-content\/uploads\/2022\/02\/definition-of-Forensic-Science-300x132.png\")
References<\/h2>\n