EDIT: We published this paper on the gendarmes investigating the origins of the fires in July 2017. While 14,000 hectares have been ravaged by fire in recent days in Gironde, we are going back to this article.
The fire ravages the south-east of France. Wind and drought may explain how the fires spread so quickly. How they got started remains to be seen. Is their origin accidental? Criminal? To begin their investigation, the gendarmes must wait until the fire is completely extinguished, explains to 20 minutes Colonel Patrick Touron, boss of the Gendarmerie Criminal Research Institute. Priority is given to rescue.
The investigators then try to locate its starting point, which is on one of the edges of the fire. “In the beginning, the fire has the particularity of not being too intense. Then it spreads in the direction of the wind or the slope. »
To find its hatching point, the gendarmes look at “the V of propagation”. Indeed, the more it spreads, the more it expands. », explains Colonel Touron.
Once the starting point of the fire has been found, the investigators are trying to determine its origin. On the spot, they seek in particular to know if the inhabitants practice the burning. “Often, they make a small fire to get rid of twigs or branches, and the situation escapes them, explains the expert. With the wind, they are unable to contain the start of the fire. »
The gendarmes are also approaching firefighters or agents of the National Forestry Office (ONF) “who know the places where people have barbecues or which serve as a meeting place for lovers”. They sometimes discover that the fire was caused by walkers who had a barbecue in the woods, and who extinguished it badly or did not cover the embers well enough with earth or sand.
The fire can also be caused by a badly extinguished cigarette butt. Often, investigators find that the fire started from a ditch, near a road. There, they find one or more cigarette butts, probably thrown by motorists. They deduce that they are the cause of the accident. Finally, they check that the fire was not caused by a tree that fell on a power line or by lightning.
18% of fires are of voluntary origin
“If there is no logical explanation, then we can suspect a criminal cause,” continues Colonel Touron. “We will then carry out investigations, as for any investigation. We are trying to find out who was present at the scene when the fire broke out. For this, witnesses are interviewed. According to him, the inhabitants are more and more aware and are now very careful of vehicles that are parked near the woods, of people walking around.
The gendarmes will also watch the images of the surveillance cameras. They also look for clues, such as “tire tracks in the grass”, he adds. They can thus go back to the arsonist. However, only 18% of the fires are of voluntary origin, according to the gendarmerie. The majority is certainly of human origin, but accidental.