Criminal Investigations: Bloodstain Pattern Analysis
Crime scenes containing blood traces hold numerous important pieces of information: the arrangement, size, shape, and location of bloodstains can be useful in reconstructing the criminal event.
The study and analysis of bloodstains is known as Bloodstain Pattern Analysis (B.P.A.), which is achieved through scientific knowledge combined with other disciplines such as biology, chemistry, mathematics, and physics. By following a predetermined analytical plan, excellent results can be obtained regarding scientific investigation.
Every stain found at the crime scene has a story to tell that emerges through the analysis of the collected material. Consequently, through laboratory analysis, it is possible to determine whether the stains originated from splashes caused by blunt objects, wounds inflicted by cutting or firearms, or if they are secondary traces (from dragging) or passive stains (from dripping), as well as whether the trauma was caused by explosions, or if the victim was attacked by a left-handed or right-handed assailant. Argo’s personnel therefore offer the capability to analyze blood traces present at a crime scene to identify and determine the location of the perpetrator and the victim, since bloodstains can confirm or exclude hypotheses and verify or invalidate information.
In Italy, the first case in which Bloodstain Pattern Analysis was employed was the murder of little Samuele Lorenzi in Cogne; due to the large amount of blood traces present at the crime scene, this case is often used as a case study for bloodstain analysis. Thanks to its scientific rigor, B.P.A. is considered one of the classical scientific proofs in criminal trials.
Regarding the Cogne case, the Court of Cassation clarified that:
“Blood Pattern Analysis cannot be considered an atypical form of evidence, but rather an investigative technique belonging to the category of expert examination; therefore, its admission does not require prior hearing of the parties pursuant to article 189, last part, of the Code of Criminal Procedure.”
(Cass. Pen. sect. I, May 21, 2008, no. 31456 – FRANZONI SENTENCE).