THE BELOW OF THE SURVEY
Cathie Louvet's chronicle
CRIMINAL INVESTIGATIONS :
Folder n°2 : genesis of the scientific police
The analysis of the traces left by the criminals developed at the end of the 19 th century. But it is anchored in practices dating back to the Middle Ages and is based on processes whose history remains unknown. I suggest you discover them.
Les The hunters of the Middle Ages :
The search for clues in traces and fingerprints is a practice inherited from medieval hunters. Indeed, hunting, in the Middle Ages, followed a very precise protocol. At first, the hunter had to observe in order to detect traces. Then, thanks to his experience, he was able to identify the animal at the origin of the traces noted. He then attempted to give as precise a description as possible: the species, the sex, but also, in the most favorable cases, its weight, pace and age.
This approach is similar to that used by the pioneers of the modern scientific police in the exploitation of material traces, namely that some, although they have a scientific background, claim loudly. So much so that criminals such as André Frécon, who wrote various treatises in the late 19th century and early 20th century, recovered this legacy by integrating the reading of animal legs into their field of research.
Hunting treaties serve as a model :
Edmond Locard, founder of the technical police laboratory in Lyon, pays tribute to them in 1937: "If we want to trace the filiation of the modern policeman up to the follower of animal traces, it is in treaties of Renaissance veneration that it would be necessary to go and discover the great ancestors of Sherlock Holmes.It is certain that the analysis of the footprints was made with much more sagacity and meticulousness by the hunters at the time when hunting was an art, noble of all, than by our best hounds of the contemporary police. "
Locard would certainly have been able to go even further, for the hunting treaties, which multiplied from the 12th century onwards, already contain numerous chapters devoted to the analysis of footprints. One of the earliest examples of a medieval hunting treatise mentioning the importance of reading the traces of the legs of game is an anonymous poem, La Chace Dou cerf, written in the second half of the 13th century:
"You will recognize by the foot
What a stag you have to run.
Large foot sills and wide heel,
this is what no one should despise.
If it has large and wide lugs,
you are mad if you renounce it. "
In order to make the most reliable report, the informed hunter advises not only to analyze the footprints but also to collect the "smoke" (excrements left by the game) or to locate the "spawning", traces that the wood of the animal leaves on the bark of the trees when rubbing the head, which gives an indication on its size.
However, medieval poems remain rather evasive; for example, they do not indicate how the hunter distinguishes a trace of deer from that of a deer. It will be necessary to await the treaties drafted in the 14th century to discover comparative analyzes of the traces of the various traces of game, as well as procedures that allow to develop the sense of observation and induction. Henri de Ferrières explains: "If you want to see the differences and learn to distinguish by traces the young deer of the deer and the great stag of the young, and if they are courageous or not, try to get you the feet of a deer, those of a young stag and those of an old stag well walking.look and examine both and the footprints first in then you will see the difference between the tracks and will be able to distinguish the hinds of the old deer and the young. "
Until very recently, we thought we knew everything about fingerprinting, in other words fingerprinting. Now, thanks to documents recently discovered, we are obliged to revise its history by taking into account the contribution of pioneers whose existence we did not know.
It is in Asia, in the 7th century, that we find the first uses of fingerprints for divorce contracts and recognitions of debt for those who are not able to sign, whereas in Europe they appear only from the 12th century, on the reverse of certain seals of wax. It should be noted that this practice of applying in the wax the trace of a finger as a sign of identity was already used in the third millennium BC by the Babylonians.
But it is in Europe that the first scientific studies on fingerprints appear. In 1686, the Italian physician and anatomist Marcello Malpighi published a study on these drawings without considering applying it to police investigations. In 1823 Johan Purkinje, professor of physiology at the University of Breslau in Silesia (now Wroclaw, Poland), proposes the first classification of fingerprints, but he does not study them permanently and he will never exploit them for identification purposes.
Yet at the same time, the first mention of the use of these fingerprints in criminal investigation appears in forensic medicine treatises. Indeed, in 1823, the toxicologist Mathieu Orfila proposes to exploit them for the cases of infanticide. He encouraged his colleagues to carefully examine the traces left on the neck of a newborn child who died of asphyxia to determine whether death was accidental or criminal. This suggestion will be taken up in the Dictionary of Medicine in 1825, of which the following is an extract: "The bruises of the neck must be particularly studied with regard to their form, in order to know whether they are circular or irregular, especially if they offer fingerprints , and if the skin is whole or skinned, we may conceive how important this research is, since the fetus may have been strangled involuntarily by the effect of the compression which it experiences from the uterine orifice, umbilical."
In 1857, a pension officer, William Herschel, used fingerprints to identify illiterate fraudsters who tried to collect their pensions on several occasions. In Japan, the Scottish physician Henry Faulds, who accidentally fell on prehistoric pottery carrying fingerprints, began to study them. In 1880, his work gave a founding article in the journal Nature in which he suggested using digital traces on crime scenes. In reality, he is not the only one to have had this idea.
In 1840, following the murder of politician William Russell, found murdered in his bed in May of the same year, doctor Robert Blake Overton suggests in a letter sold at auction in 2012 to use the fingerprints of suspects in order to to compare them with the traces raised on the sheets and the pillow of the scene of the crime. The policemen followed his advice, but unfortunately did not find any traceable traces. But the impulse was given ...
Paul-Jean Coulier :
Whether it is his work in physics or his publications on diet or the applications of the microscope in medicine, nothing in the scientific production of Paul-Jean Coulier, titular doctor of the chair of toxicology and chemistry of the Val-de-Grace School of Medicine in Paris, indicated that he was going to make a decisive contribution to this new discipline of scientific forensics. In an article published in 1863 in The Scientific and Industrial Year, Coulier refers to the possibility of exploiting fingerprints to identify the author of falsified documents. He has the idea to analyze falsified documents using iodine vapor, used at the time to sensitize daguerreotypes to light. It takes advantage of the fact that these vapors reveal physical changes on a surface. The advantage of the experiment which it develops is that it requires little material and time: it is sufficient to deposit iodine crystals in a basin and to cover it with the document to be examined . Within 15 to 60 minutes, the naturally evaporated iodine settles on the surface of the paper and sails where the forger has erased or scratched. In some cases, the vapors would even reappear the deleted text !
In addition, Coulier found that, under the effect of vapors, spots had appeared on the document, precisely in the places touched by the manipulator during the experiment, reproducing faithfully the papillae of the skin. Conscious that these lines form varied motifs to infinity, he deduces that "it would not be impossible to recognize to these vestiges the individual who would have touched the paper." He then suggests comparing the fingerprints of the suspect, taken on a sheet and revealed by the iodine vapor, and the traces on the falsified document.
Although the method of revealing traces and comparing them with a suspect's fingerprints is entirely relevant, Coulier has not yet determined the durability of digital drawings, as he believes that these can change over time. time. It is true that this method has disadvantages: in the case where the finger slides on the document, its trace would then be too confused to allow a reliable identification. Moreover, as the fingerprints revealed disappear more or less quickly in the open air, it is essential to photograph them as soon as possible.
The most surprising thing is that this primordial discovery was not noticed by the police or by justice. Apart from a mention in the Annals of Public Hygiene and Forensic Medicine in 1864, few police officers were aware of the procedure. It was not until the 1900s that this discovery became part of the panoply of experts' tools.