On Wednesday, prosecutors in France said the catastrophic fire that occurred at Notre Dame in April may have been caused by an electrical malfunction or a cigarette.
Paris prosecutor Remy Heitz said in a statement that a preliminary investigation has found no evidence that the fire was started intentionally.
That investigation, which concluded on Wednesday, involved around 100 witness hearings. Prosecutors are now reviewing the possibility of negligence and will be opening a judicial investigation.
The statement said the judicial investigation will be be conducted "on the grounds of involuntary damage by fire due to a manifestly deliberate breach of a duty of care or safety imposed by law or regulation."
Additional reporting from Newsy affiliate CNN.