Robert P. Spalding earned a name for himself in forensic science by trying his hand in bloodstain pattern analysis. Robert Spalding joined the FBI in 1971, and in 1975, he was assigned to teach FBI field office evidence response teams around the country. His contributions had a significant impact on how crime scenes are examined. Robert P. Spalding has also written several books on the subject of blood analysis.
- Bloodstain pattern expert
- Taught to the Evidence Response Teams
- Owner of Spalding Forensics, LLC.
- B.S. (1965) and M.S. (1968) from the University of Maine in biochemistry
- 1971: Joined FBI as an agent
- 1973: Transferred to Laboratory Division (Serology Unit)
- 1975: began to teach at Forensic Science Research and Training Center (FSRTC)
- 1999: Retired from the FBI
BPA allows police investigators to recreate the locations and activities of the people and weapons involved by working backward from blood evidence at a crime scene. Drips, smears, and spatters are generated as blood drops radiate from the impact of a bullet or blunt instrument until they come into contact with a surface and stain it. BPA, however, lacks scientific rigor and appropriate accreditation for its practitioners, according to a disturbing 2009 report from the US National Academy of Sciences (NAS) that still resonates today.
This is a serious concern since BPA results have been used to convict people who were later found to be innocent, as many believe Bryan is, and because a lack of trust in BPA analysis could allow the guilty to go free. As a result, it’s become critical to reconsider the physics of BPA.
Even though the United States has the highest rate of gun ownership in the world (120 firearms per 100 persons) and gun-related homicides account for 64% of all homicides in the country, other countries also have a high rate of shootings. For example, weapons are used in 30% of homicides in Canada, and a dozen countries, including Brazil, have a higher rate of gun deaths per 100,000 inhabitants than the United States.
By helping to categorize the world’s 250,000 annual gun-related deaths as homicides or suicides – and, in the former case, potentially bringing the perpetrators to justice – establishing the scientific validity of BPA could have a global impact on dealing with the world’s 250,000 annual gun-related deaths.
BPA reconstruction is a difficult topic in fluid mechanics that entails tracking the behavior of blood under various stresses and environmental variables. Blood is a complicated fluid that contains both liquid (plasma) and solid (blood cells) components, making the task more difficult. Furthermore, blood qualities such as pH and the number of red blood cells differ from one person to the next.
This endeavor, however, is more than a mere intellectual exercise. According to Alicia Carriquiry of Iowa State University in the United States, it can also have real-world consequences.
Carriquiry has a comprehensive view of forensic science as a statistician and head of the Center for Statistics and Applications in Forensic Evidence (CSAFE), which is supported by the US National Institute of Standards and Technology (NIST). She explains, “BPA is one of those areas where science has a lot to say.” “Unlike other forensic disciplines, we have physical and fluid-dynamical models in BPA that can help us address questions like trajectory, location of origin, and similar questions.” Blood follows specific scientific rules, thus qualified bloodstain pattern analysts can analyze the blood evidence left behind and derive inferences about how the blood was shed.
Analysts can categorize bloodstains from what appears to be a random distribution at a crime scene by gathering information from spattering patterns, transfers, voids, and other signs that aid investigators in recreating the sequence of events that transpired after bloodshed. This type of physical evidence necessitates the analyst’s ability to notice and understand patterns to figure out how they were generated.
The interpretation of bloodstains at a crime scene to reproduce the events that generated the bloodshed is known as bloodstain pattern analysis (BPA). The size, shape, distribution, and placement of the bloodstains are used by analysts to create views about what happened or did not happen.
BPA helps scientists answer problems like: Where did the blood come from? by using principles of biology (blood behavior), physics (cohesion, capillary action, and velocity), and mathematics (geometry, distance, and angle).
- What was the source of the wounds?
- What direction did the victim’s injuries come from?
- What was the position of the victim(s) and perpetrator(s)?
- What steps were taken in the aftermath of the bloodshed?
- How many potential criminals were there?
- Does the bloodstain evidence corroborate or disprove the testimony of the witnesses?
Blood follows specific scientific rules, thus qualified bloodstain pattern analysts can look at the blood evidence left behind [and form inferences about how the blood was shed]. Analysts can categorize bloodstains from what appears to be a random distribution at a crime scene by gathering information from spattering patterns, transfers, voids, and other signs that aid investigators in recreating the sequence of events that transpired after bloodshed. This type of physical evidence necessitates the analyst’s ability to notice and understand patterns to figure out how they were generated.
Spatter Bloodstain Patterns
Despite passive bloodstain patterns, which normally fall as drops owing to gravity, spatter bloodstain patterns are frequently caused by added force or motion to the bleeding source. Impacted bloodstain patterns are included in the category of spatter bloodstain patterns, indicating that a considerably more energetic force was utilized to shatter the blood into smaller-sized blood spatters or spheres.
The size of the blood spatters will be determined by the amount of energy involved in the force. Smaller patterns, in particular, imply that a greater amount of force was applied. Blood spatters that have been affected are usually classed as a medium- or high-force impact spatters.
Blood drops in medium-velocity impact spatters are often significantly smaller than those found in passive bloodstain patterns, as they are commonly the consequence of blunt or sharp force injuries. High-force impact spatters, which have a mist appearance, are commonly caused by firearms, although they can also occur as a result of explosions or high-speed accidents.
BPA not only tells you what happened, but it also tells you what could have happened. This information can help the investigator reconstruct the crime, corroborate witness testimony, and determine whether or not potential perpetrators should be included in the investigation.
Bloodstain patterns can be recognized and analyzed to provide useful investigation information. In a criminal investigation, the general role of the Bloodstain Pattern Analyst is to assist in the reconstruction of those events of an alleged incident that could have caused the stains and stain patterns present at a crime scene, on items of physical evidence recovered from that scene, and on clothing that was present at the crime scene. It may be required to use images to evaluate bloodstain patterns in some circumstances. Individual bloodstains and bloodstain patterns are useful because they retain information descriptive of the events that could have caused them.
The sizes of the individual stains that make up a pattern, their forms, and their distribution relative to one another can all be used to figure out how a stain or pattern was made. Bloodstain pattern analysis is used to figure out what action(s) or sequence of activities could have resulted in the bloodstains and/or patterns shown. The position of the individual when the blood was deposited (sitting, standing, etc. ), the relative positions of individuals at the time of bloodshed, the possible type of weapon used, and possible mechanisms that could have produced the blood staining on a surface are all things that bloodstain pattern analysis can reveal.
An accurate BPA will include not just the gathering of knowledge on a single stain, but also suitable documentation of the entire area where the bloodstain was discovered. Many crime scenes that used traditional photographic documenting of bloodstain patterns resulted in false judgments.
Bloodstain patterns give forensic investigators information on the “what and how” of the bloodbath incident rather than information on the victim and/or culprits. More precisely, BPA data is utilized for crime scene reconstruction operations, which go beyond guessing what happened during a crime and instead rely on evidence, reasoning abilities, and investigative knowledge to figure out what happened.
Due to these restrictions, scientists have turned to three-dimensional (3D) and optical sensing approaches. Laser scanning technology, which generates a complete digitalization of the scanner’s surroundings, is the most popular 3D approach employed during crime scene investigations. Forensic investigators frequently use commercial software like Faro Scene, which combines traditional pictures with 3D data, to supplement the data obtained by 3D laser scanning.
A 3D multi-resolution scanning platform that incorporates numerous laser scans to acquire information on the bloodstain pattern from various positions has recently been developed. This model, in particular, allows forensic investigators to digitally examine a crime scene to gain a more accurate picture of the bloodstain pattern and any surrounding circumstances that can be utilized to identify specific facts about the crime that was committed.