He instructed a workman to lift the tiles, presuming that blood would have pooled underneath, and he was correct. Both the analysis of blood and its patterns come under the umbrella of the discipline of serology, or the science of biological fluids.
The first method for distinguishing animal blood from human was proposed in 1841: it was heated up with a chemical and sniffed for a specific odor, but there proved to be no scientific basis to this claim. During the next decade, Ludwig Teichmann mixed blood with a solution of potassium chloride, iodide, and bromide in galactic acid, showing that hemoglobin could be changed into hemin in order to examine the shape of the resulting crystals. While useless as yet for forensic investigation, this method stood for half a century before another scientist improved upon it.
Different blood types were recognized as early as 1875, but it wasn’t until 1901 that Dr. Karl Landsteiner, at the Institute of Pathology and Anatomy in Austria, named and standardized the groups. He asked colleagues for samples of their blood, and with a centrifuge he separated the clear serum from the red cells. He then placed the samples in a number of different test tubes, mixing the blood of one participant with the blood of all the others. He found that sometimes blood clumped together and sometimes the samples repelled one another. He determined from these experiments that there were three types of blood, based on differences in a substance called an antigen, which produces antibodies to fight infection. He labeled them types A (antigen A present, anti-B antibody present, but antigen B absent) and B (antigen B present, antigen A absent). A third distinct reaction was labeled C (both antigens A and B absent), but was later relabeled as O.
It took another two years, but a colleague of Landsteiner’s, Dr. Adriano Sturli, discovered yet another type in which both antigens were present, so he called it type AB. It soon became clear that the blood type depended on genetic inheritance from parents, which helped with paternity tests. Types A and O are the most common in the human population, and AB the rarest.
At the same time that Landsteiner was experimenting with blood types, another young doctor was working on the distinction between animal and human blood. German biologist Paul Uhlenhuth, working at the Institute of Hygiene in Griefswald, had taken up the study of hoof-and-mouth disease, and he hoped to develop a serum to combat it. Before him, Jules Bordet, from Belgium, had shown that a vaccination elicited a specific antibody and had worked with the behavior of antigens. He was able to see a visible reaction between the antibody and antigen. Others who injected animals against infectious diseases found that foreign substances caused the production of defensive substances specific to the injected material. These “precipitins” could be utilized to distinguish different types of protein.
Uhlenhuth continued to pursue the implications of this research with other experiments, learning that if he injected protein from a chicken egg into a rabbit, and then mixed serum from the rabbit with egg white, the egg proteins separated from the liquid to form a precipitin. As he proceeded, he found that the blood of each animal had its own characteristic protein, and then, after injecting human cells into the rabbit, he realized that the test was also applicable to humans.
This was welcome news for law enforcement, because crime suspects often claimed that blood on their clothing was from animals, and as yet their stories could not be scientifically disputed. With the precipitin test, those days appeared to be over. To be certain about this result, a coroner asked Uhlenhuth to test some dried bloodstains from both animals and humans, and the results proved the test to be reliable.
Then, just four months after Uhlenhuth announced his discovery, a particularly brutal crime brought the test into the forensic
The first method for distinguishing animal blood from human was proposed in 1841: it was heated up with a chemical and sniffed for a specific odor, but there proved to be no scientific basis to this claim. During the next decade, Ludwig Teichmann mixed blood with a solution of potassium chloride, iodide, and bromide in galactic acid, showing that hemoglobin could be changed into hemin in order to examine the shape of the resulting crystals. While useless as yet for forensic investigation, this method stood for half a century before another scientist improved upon it.
Different blood types were recognized as early as 1875, but it wasn’t until 1901 that Dr. Karl Landsteiner, at the Institute of Pathology and Anatomy in Austria, named and standardized the groups. He asked colleagues for samples of their blood, and with a centrifuge he separated the clear serum from the red cells. He then placed the samples in a number of different test tubes, mixing the blood of one participant with the blood of all the others. He found that sometimes blood clumped together and sometimes the samples repelled one another. He determined from these experiments that there were three types of blood, based on differences in a substance called an antigen, which produces antibodies to fight infection. He labeled them types A (antigen A present, anti-B antibody present, but antigen B absent) and B (antigen B present, antigen A absent). A third distinct reaction was labeled C (both antigens A and B absent), but was later relabeled as O.
It took another two years, but a colleague of Landsteiner’s, Dr. Adriano Sturli, discovered yet another type in which both antigens were present, so he called it type AB. It soon became clear that the blood type depended on genetic inheritance from parents, which helped with paternity tests. Types A and O are the most common in the human population, and AB the rarest.
At the same time that Landsteiner was experimenting with blood types, another young doctor was working on the distinction between animal and human blood. German biologist Paul Uhlenhuth, working at the Institute of Hygiene in Griefswald, had taken up the study of hoof-and-mouth disease, and he hoped to develop a serum to combat it. Before him, Jules Bordet, from Belgium, had shown that a vaccination elicited a specific antibody and had worked with the behavior of antigens. He was able to see a visible reaction between the antibody and antigen. Others who injected animals against infectious diseases found that foreign substances caused the production of defensive substances specific to the injected material. These “precipitins” could be utilized to distinguish different types of protein.
Uhlenhuth continued to pursue the implications of this research with other experiments, learning that if he injected protein from a chicken egg into a rabbit, and then mixed serum from the rabbit with egg white, the egg proteins separated from the liquid to form a precipitin. As he proceeded, he found that the blood of each animal had its own characteristic protein, and then, after injecting human cells into the rabbit, he realized that the test was also applicable to humans.
This was welcome news for law enforcement, because crime suspects often claimed that blood on their clothing was from animals, and as yet their stories could not be scientifically disputed. With the precipitin test, those days appeared to be over. To be certain about this result, a coroner asked Uhlenhuth to test some dried bloodstains from both animals and humans, and the results proved the test to be reliable.
Then, just four months after Uhlenhuth announced his discovery, a particularly brutal crime brought the test into the forensic
Similar Books
