Blood trail
A trail of blood is a lesser or greater amount of blood that suggests an injury that resulted in blood loss . Blood traces have been used since ancient times to infer certain facts, from which blood trace science developed.
Animal blood
In the language of the hunters, a trail of blood is called “sweat” and is used to track a wounded animal. The visibility of the lost blood on the ground or on plants can serve as a track. When using a hunting dog, this depends on the individual odor of the animal and ideally also “refers” to otherwise invisible traces of blood (“ sweat ”). This is where the term bloodhound comes from .
Human blood
regional customs
From the earliest times, the trace of blood on the sheet after the wedding night has been taken as evidence of the consummation of the marriage by defloration of the bride. In some regions of the world it is still customary today that the groom has to show his parents a bloody bed sheet to prove his wife's virginity, or even hang the same out of the window. If the woman no longer enters the marriage as a virgin , the situation is often simulated with animal blood. In Europe, this custom is still widespread in southern Italy .
Criminology
Even in the early days of criminology , traces of blood were used to infer the course of violent crimes . There are different ways of doing this.
Conclusions from the geometric shape of blood stains or blood splatters
The assessment of the geometric shape of the traces of blood, whether it is round drops, with or without splashes around them, elongated drops or blood smears, allows conclusions to be drawn about what happened and, if applicable, which weapon was used and how in a crime. One of the pioneers in this field was the Berlin court chemist Paul Jeserich .
- Example: An elongated drop indicates that a blood-stained object has been moved, for example an ax wielded. Conclusion: The victim was hit more than once.
Conclusions from the composition
If such traces are present, it must first be decided whether it is blood (and not rust stains, for example) and whether it comes from humans or animals. The Krakow anatomist Ludwik Teichmann made the first method for the detection of blood (or haemin ) in traces known in 1853 .
Since the beginning of the 20th century, it has become increasingly clear that not all blood is created equal and that there are ways of determining differences beyond doubt. In 1901 Paul Uhlenhuth created the Uhlenhuth test , which was carried out using blood serum from rabbits and which allowed animal and human blood to be clearly differentiated. This clearly refuted the protective claim of the violent criminal Ludwig Tessnow that a trace of blood was animal blood. In the Wassing-Falkenberg murder case (1956), too, a false accusation could only be cleared up by distinguishing between dog and human blood.
With the discovery of blood groups by the Viennese Karl Landsteiner in 1900 it became possible to differentiate between human blood and to exclude a certain origin of a blood trace in different blood groups (named by the Pole Ludwik Hirszfeld ).
The methods were continuously refined so that ever smaller traces were sufficient for an analysis. In 1916, Leone Lattes, an assistant at the Forensic Medicine Institute in Pavia, found a method (the Lattes test ) to determine the blood group of traces of blood that had already dried out.
The absorption method developed by Innsbruck forensic doctor Franz Josef Holzer in 1930 and first forensically used in 1931 (in the Mair murder in Imst ) for the group determination of blood traces offered better possibilities , with which the blood group properties in the red blood cells and thus also with small amounts of blood could be identified.
Later (1939) it was discovered that in addition to blood, the blood group can also be determined from saliva (e.g. on cigarette butts) and other body secretions. So was Alexander S. Wiener , head of the serological laboratory Chief Medical Examiner of New York, Milton helpers, by the blood typing of secretion stains help educate the up occurred in New York in 1943 murder of the Greek Alice Persico. In experiments on skin transplantation, Robin Coombs discovered the principle of mixed agglutination in 1955 , which by 1965 had developed into another sensitive test in forensic blood grouping, for example on tiny fibers. Today, a DNA analysis can also be carried out from a trace of blood , which clearly identifies the person belonging to it.
Visualization of weak traces of blood
The oldest but unsafe method is the application of hydrogen peroxide to a suspected area. Where the liquid begins to foam, there is either a trace of blood or some other reducing substance.
In the Kastle Meyer test, hydrogen peroxide oxidizes reduced phenolphthalein (colorless) quickly to phenolphthalein (red) in the presence of traces of blood. The new process, in which luminol is sprayed onto a suspected area, is more reliable : if the trail starts to glow, the suspicion of blood is confirmed.
Web links
Individual evidence
- ↑ Jürgen Thorwald : The hour of the detectives. Becomes and worlds of criminology. Droemer Knaur, Zurich and Munich 1966, pp. 31–35.
- ↑ Jürgen Thorwald: The hour of the detectives. Becomes and worlds of criminology. 1966, pp. 31-35.
- ↑ Jürgen Thorwald (1966), pp. 31-62.
- ↑ Jürgen Thorwald (1966), p. 160 f.
- ↑ Jürgen Thorwald (1966), pp. 62–70.
- ↑ Jürgen Thorwald (1966), pp. 64–81.
- ↑ Jürgen Thorwald (1966), p. 80 f. and 128 f.
- ↑ Jürgen Thorwald (1966), p. 128 f. and 160 f.
- ↑ Jürgen Thorwald (1966), pp. 269-274.