BloodStain Pattern Analysis tecnica cos'e e come funziona

Bloodstain Pattern Analysis, the technique that analyzes blood traces at the crime scene

Bloodstain analysis, known as Bloodstain Pattern Analysis (BPA), is a technique forensic which allows you to rebuild a crime through the study traces of blood, then splashes and stains of blood. Specifically, BPA studies the morphology, distribution and position of traces. In fact, every drop of blood at a crime scene can reveal details crucial to the events that led to a tragedy. In this article, we will explore the main categories of blood trail classification and the information that can be derived from them.

Bloodstain Pattern Analysis

Drip Traces

The first type of blood traces that we analyze in the video are those from drip. When a drop of blood falls freely under the action of gravity, it leaves a characteristic trace on the surface underlying. For example, a drop of blood fallen from a meter on a surface of wood create a stain circular with edges irregularbecause the wood absorbs partially the blood following its veins. If the same drop falls from two metersthe stain will be similar but will have visible differences due to the greater height.

Another variation is observed by changing the surface: on one tile, a drop of blood can generate satellite trackssmall drops around the principalindicating that multiple drops have fallen in the same spot. This information may suggest, for example, that the victim was immovable in a certain position while blood was dripping from a wound.

Blood Splatter - Drip Bloodstain Pattern Analysis

Transfer tracks

The traces from transfer They form when blood is transferred from a object or a body part to aother surface. A common example is a slap on a tile: the hand dirty of blood enters contact with the surface, transferring the blood. If there was movementthe stain will have a direction precise, as in the case of a hand moving downwards, creating a trace faded called “swipe“. This typology may suggest that the victim was dragged.

Transfer Trace - Blood Bloodstain Pattern Analysis

Sketch traces

The traces from sketchor simply “sketch” occur when a Force he comes applied to a volume of liquid blood, creating a distribution of impact. Using a hammer, for example, generates distinct splashes, while an object placed in front of the impact area can create a “shadow” free of splashes. Even a moving weapon, such as a knife, produces splashes directional due to force centrifuge. These traces can provide details about the nature and direction of the force applied during the violent act.

Bloodstain Pattern Analysis Bloodstain Pattern Analysis

History and Critical Issues of BPA

BPA has historical roots dating back to 1895when the German doctor Edward Piotrowski published the first study systematic on traces of blood resulting from injuries. Although initially the technique was rudimentaryover the decades has been perfected thanks to scientific progress and technological. Today, organizations like theInternational Association of Bloodstain Pattern Analysts (IABPA) and theAmerican Academy of Forensic Sciences (AAFS) recognize BPA as a reliable technique.

However, the BPA presents some critical issues. The interpretation of the tracks is subjective and can vary from analyst to analyst, leading to conclusions different. Furthermore, there is a lack of standardization universal of the analysis methods, which may influence the results. These limitations have raised doubts on the reliability of BPA, especially in cases where it has been used as the main evidence, leading to sentences Then canceled or criticize.

Transfer Trace - Blood Bloodstain Pattern Analysis Criticality

Despite its critical issues, the BPA it still remains one instrument precious when integrated with other forensic analysis techniques, such as chemical and biological DNA analysis. Used correctly, it can provide information crucial for the reconstruction of a crime.

However, we would like to point out that those shown in this video are only someone of the types of blood traces, probably the most simpleThe traces that can be found at a crime scene are numerous and provide various information, such as theimpact angle, the convergence zone or the time elapsed since the track was deposedbased on the amount of coagulated blood. Bloodstain Pattern Analysis is a complex technique that requires high scientific skills, especially in physics and chemistry.