French authorities have no grounds to believe that the fire that wrecked Paris' Notre-Dame Cathedral in April was the result of criminal activity, although they are looking into the possibility of negligence, according to the Paris prosecutor's office.
"Several hypotheses have caught the attention of the investigators, including that of a malfunction in the electrical system or that a cigarette that was not properly put out could have started the fire," Paris prosecutor Remy Heitz said in a statement.
"Even if certain failings, which may explain the scale of the fire, have been brought to light, the investigations carried out to date have not yet been able to determine the causes of the fire," Heitz said, adding that further probes would be carried out.
Richard Marlet, former head of the scientific police in France, told Euronews that investigators will need to carefully examine which electrical circuits were in Notre Dame at the time of the fire. "It might be wires connected to the tools used by the companies in charge of renovation works," the expert said, or "it might also be the electrical circuit connected to the bells."
Marlet described the colossal work still ahead for investigators: Scientific police will need to reconstitute these circuits, examining films, photographs and maps gathered in investigations, the expert said.
They will continue searching the rubble in an attempt to determine what types of electrical circuits could be associated with each of the fragments from the cathedral. Meanwhile, authorities will review transcripts from hundreds of interviews conducted so far in order to list exactly what was stored in the building, which could have activated the fire.
"It will be very long task," Marlet warned.
A massive fire consumed Notre-Dame on the evening of April 15, destroying the roof of the Paris landmark and stunning people in France and the world. Firefighters saved the main bell towers and outer walls from collapse before bringing the blaze under control.
President Emmanuel Macron has set a target of five years to restore Notre-Dame, which dates back to the 12th century and is one of Europe's most iconic landmarks.