2023-07-18 06:30:34
Fires are difficult to investigate, as they often destroy evidence of their cause. However, Swiss scientists have demonstrated how connected objects can reveal valuable clues.
On June 21, 2023, a fire in a building located rue Saint-Jacques in Paris injured dozens of people. On January 12, 2019, a fire rue de Trévise in Paris left four dead, 66 injured and nearly 400 victims. In both cases, a gas leak would be the cause of these claims.
But the investigations are sometimes very long to determine if the origin is criminal or accidental. Taking into account the physical and chemical knowledge of fire and the propagation of heat, a backward reasoning is applied to define, by hypothesis, the place where the fire broke out.
The artefacts produced by the spread of the fire on the electrical installations (circuit breaker tripping sequence, mapping of electric arcs, etc.) are also very often taken into account, as well as the statements of witnesses and first responders.
Traces for the investigation
Another avenue is still too often overlooked: Internet of Things (IoT) devices for home use. In France, in a study published in January 2022, ADEME and Arcep estimate the number of these devices at 244 million.
Of this equipment, only 21% is intended for security (cameras, detectors) according to the 2022 edition of the Arcep digital barometer. They are nevertheless so many “sentinels” to better understand the origin of a fire.
This is the track studied by scientists from the University of Lausanne, Switzerland. By storing data in the cloud or sending videos to the homeowner’s smartphone, equipment might provide valuable information to investigators before being destroyed by the flames.
The Swiss team’s study highlights the potential of data captured by IoT devices for investigation. These devices have “eyes and ears” and can provide valuable forensic information.
In an experiment conducted in an apartment in a building slated for demolition, researchers examined how useful such equipment was in the event of an arson attack involving gasoline.
Applications mobiles
In this scenario, they found that the devices (temperature and motion sensors, smart cameras, smoke detectors and a voice assistant) helped reveal the exact moment the fire started, the room it started in was triggered and the timeline of its spread.
Information was retained and recovered even when the devices were completely destroyed. But researchers have not always been able to directly access data stored in local memory because of data protection systems.
In addition, this team was able to easily recover data from the smartphones of the owners of the connected devices. In one experiment, the Swiss team found that a smart device app collected a wealth of temperature, humidity and movement data, while another app provided video recorded during the fire.
In another experiment, the smart plug app recorded the time and room where the smart plug activation request was made. Data from heat and carbon dioxide sensors had suggested the fire started regarding six minutes following the plug was activated.
Moreover, the IoT devices installed in the apartment had revealed that the fire grew quickly following ignition, and not slowly, as might happen if, for example, a cigarette was left on a sofa.
These two experiments therefore highlighted the usefulness of IoT devices as potential digital witnesses and new sources of clues for investigators.
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