Bloodstain Pattern Analysis
“What processes must be undertaken to analyse bloodstain patterns at a crime scene for the purpose of presenting this evidence at a criminal trial under South Australian law?”
Blood. Sticky, hot, messy, awful blood. For most of us, the sight of it turns the stomach, but in the court of law, blood can tell a lot more about a crime scene than you might think. Forensic bloodstain pattern analysis (BPA) is the interpretation of bloodstains for the purpose of reconstructing the events that took place in the case of violent crimes.1 Using the sciences of fluid dynamics and trigonometry, BPA examiners form opinions about what did or did not happen by examining elements of the stains such as the size, shape, distribution …show more content…
There are two main types of classification for blood spatter patterns: when a force is applied to a liquid blood source, it is categorised as impact spatter.12 When there is blood spatter caused by expirated spray, arterial spurting or spatter cast off an object, it is categorised as projection spatter.13 The characteristics of blood spatter depend on the speed at which the blood leaves the body and the type of force applied to the blood source.14 In regards to gunshot spatter, there are two major patterns to observe: back spatter from the entrance of a gunshot wound and forward spatter from the exit wound.15 This kind of spatter pattern will differ depending on variables such as, where the victim is struck, whether the bullet exits the body, the caliber of the gun, distance from the victim to the gun and location of the victim in terms of objects, walls and floors.16 In most cases, back spatter consists of fewer, large drops of blood while forward spatter is a fine …show more content…
When these droplets strike a surface, the shape of the stain changes depending on the angle of impact, velocity, distance travelled and type of surface impacted.34 Generally, the stain shape will vary from circular to elliptical, with tails or spines extending in the direction of travel.35 By measuring the width and length of the stain, the angle of impact can be calculated, helping investigators determine the actions that may have taken place at the scene.36 As the angle of impact changes, so does the appearance of the resulting stain. A blood drop striking a smooth surface at a 90° angle will result in an almost circular stain.37 Below 75°, spines begin
“What processes must be undertaken to analyse bloodstain patterns at a crime scene for the purpose of presenting this evidence at a criminal trial under South Australian law?”
Blood. Sticky, hot, messy, awful blood. For most of us, the sight of it turns the stomach, but in the court of law, blood can tell a lot more about a crime scene than you might think. Forensic bloodstain pattern analysis (BPA) is the interpretation of bloodstains for the purpose of reconstructing the events that took place in the case of violent crimes.1 Using the sciences of fluid dynamics and trigonometry, BPA examiners form opinions about what did or did not happen by examining elements of the stains such as the size, shape, distribution …show more content…
There are two main types of classification for blood spatter patterns: when a force is applied to a liquid blood source, it is categorised as impact spatter.12 When there is blood spatter caused by expirated spray, arterial spurting or spatter cast off an object, it is categorised as projection spatter.13 The characteristics of blood spatter depend on the speed at which the blood leaves the body and the type of force applied to the blood source.14 In regards to gunshot spatter, there are two major patterns to observe: back spatter from the entrance of a gunshot wound and forward spatter from the exit wound.15 This kind of spatter pattern will differ depending on variables such as, where the victim is struck, whether the bullet exits the body, the caliber of the gun, distance from the victim to the gun and location of the victim in terms of objects, walls and floors.16 In most cases, back spatter consists of fewer, large drops of blood while forward spatter is a fine …show more content…
When these droplets strike a surface, the shape of the stain changes depending on the angle of impact, velocity, distance travelled and type of surface impacted.34 Generally, the stain shape will vary from circular to elliptical, with tails or spines extending in the direction of travel.35 By measuring the width and length of the stain, the angle of impact can be calculated, helping investigators determine the actions that may have taken place at the scene.36 As the angle of impact changes, so does the appearance of the resulting stain. A blood drop striking a smooth surface at a 90° angle will result in an almost circular stain.37 Below 75°, spines begin