As Mephistopheles said to Dr. Faustus “blood is a very special fluid.” Long before there was an appreciation of its astonishingly complex biology, blood was regarded with reverence as the life giving humor that it is. Severe trauma can cause blood to exit the body as drops, sprays and splatters, or flow into puddles. In any case, there was little to make of such a sight other than outward signs of tragedy. That is, until 1895 when a certain Polish professor decided that some rabbits needed to contribute to a new science—blood stain analysis.
Some 90 years later, in 1983, twenty two interested parties met for a technical conference at the Hilton Hotel in Corning NY, home of the organizer, a chemist at Corning Glass. Unlike most such meetings in this particular city, they were not there to discuss the glass industry. They came from coast to coast from the offices of police, sheriffs, medical examiners, prosecutors and crime laboratories including that of the US Army. They came to promote a new forensic science by chartering the International Association of Bloodstain Pattern Analysts—IABPA. It has grown now to 800 members in six regions world-wide.
Progress in blood pattern analysis (BPA) often stalled during the almost ninety year interval between the first scientific investigations to organizational prowess—from the great rabbit massacre to the use of trigonometry to calculate impact angles. Renewed interest began in earnest in 1954. That’s when Dr. Sam Shepard was put on trial for murdering his pregnant wife.
But let’s return to Krakow in 1895. The university there (now called Jagiellonian University) is one of the oldest in the world, alma mater to Copernicus. During Dr. Eduard Piotrowski’s time it was under the influence of the Habsburg Empire and thriving culturally. At the Institute for Forensic Medicine Piotrowski published “Concerning the Origin, Shape, Direction and Distribution of the Bloodstains Following Head Wounds Caused by Blows.”
Until then there had been little scientific interest in a topic that has earned literary references since the Old Testament—of Cain and Able: “And now you are cursed from the ground, which has opened its mouth to receive your brother's blood from your hand”. Shakespeare’s Lady MacBeth cannot rid herself of blood stains: “Out, out damn spot!”. And curiously, the Sherlock Holmes story A Study in Scarlet was published just a few years before Piotrowski’s work. The story contained astute observations on blood stains, andone has to wonder if Piotrowski ever read it.
In any case, white sheets and dead rabbits turned observation into experimental science. We learn for example that blood stain patterns often reflect the second blow. (The first blow is the one that draws blood). But his work was not mainstreamed into forensic science.
Decades later Dr. Victor Balthazard (1939) published work on angle of impact. Then LeMoyne Snyder in his book Homicide Investigation (1941), took up the topic, describing drying rates, color changes and motion patterns.
Murder on Lake Erie
But it was the case of Ohio vs Samuel Sheppard in 1955 that established the modern day bona fides of blood pattern analysis. The trial was famous—and a mess. Sheppard was first convicted by the Cleveland Press, then by the court. They determined that he, and not a ‘bushy–haired’ intruder, had bludgeoned his wife to death on the Fourth of July in their home on the shore of Lake Erie. On appeal, the US Supreme Court called his trial ‘a carnival’ and his new attorney, F. Lee Bailey, told the jury that the prosecution’s case was "ten pounds of hogwash in a five-pound bag.” But it was the solid forensics of Dr. Paul Kirk that underpinned an innocent verdict. He used blood velocity and angle of impact data to show, amongst other things, that the attacker struck with the left hand. Dr. Sheppard had a well document and significant motor–sensory deficit in his left arm.
The Glass Chemist
The unfinished business of formalizing the field was left to Herbert Leon MacDonell who In 1971 wrote Flight Characteristics of Human Blood and Stain Patterns. It was MacDonell who organized the meeting in Corning NY, creating a profession that could help catch a criminal, or free the innocent.
Take the case of Mrs. Mowbray. She would have been spared nine years in prison before a reversal when it was discovered that MacDonells’ expert testimony had been suppressed. Another famous case of wrongful conviction that hinged onBPA was that of Lindy Chamberlain. Her claim that a ‘dingo ate my baby’ was not believed. And yet a belated review of the blood evidence exonerated her, after three yearsof incarceration.
As to the use of BPA to catch a murderer, the methods have been crucial to establishing positions of victim and attacker, assault maneuvers, and even identities from transfer stains with foot and hand prints—all clues that help direct further investigation.
Nowhere is BPA more dramatic than in the TV series Dexter. Dexter Morgan was an off-kilter blood stain analyst who used his considerable skill to find the evil-doer. Born with innate homicidal tendencies, he sublimated them into acts of vigilante justice. For a real life expostion see the presentation on YouTube, Better Than Dexter.
IABPA, NAS, FBI
The field has been pioneered by non-academics and adopted by law enforcement. But it’s popularity out-paced any standardization, leading the National Academy of Science to question it’s validity. But the FBI weighed in with support via a Scientific Working Group on Bloodstain Analysis (SWGSTAIN) which is now the standard bearer for competence in the physics, math, biology and chemistry that have made BPA a staple of modern forensics. BPA has even found its way into college curricula such as Marshall University’s forensic science graduate program. Their Crime Scene House is famous.
Residue and Splatter
There is also a body of literature on blood residue, I.e. blood group and DNA analysis and animal of origin tests. An brief historical review of identifying blood vs not blood and human vs animal comes from, of all places, the Crime Fiction Writer’s Forensics Blog. The hematin test was developed in 1853, the guaiac test in 1862. For a more modern review see this Sherlock Holmes fan site—Sherlock's test in A Study in Scarlet was not a real one. And, in 1900, Uhlenhuth developed an antigen–antibody precipitin method that distinguishes human from animal blood.
A thumbnail sketch of blood pattern analysis goes like this:
The diameter of a blood droplet is proportional to the height from which it fell. Drops undergo contact, displacement, dispersion, andretraction. A pattern can result from contact or from being cast off.
The elliptical shape of a blood spot can give direction from calculating the angle of impact: Angle of Impact = ArcSin (Stain Width / Stain Length). Angles of impact from multiple drops allow calculation of an area of convergence and thus an area of origin. This is where the strings come in, or a computer. Strings are better for movies.
And, of course, there is a Wikipedia page for that.
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"The trial that followed was a media circus--one often compared to the O.J. Simpson trial. The popularity of the case would go on to be one of the alleged inspirations of the TV show "The Fugitive" (and later the Harrison Ford movie of the same name)."