June 27 (UPI) -- The blaze that consumed Paris' Notre Dame Cathedral two months ago might have been started by a burning cigarette or electrical malfunction, authorities said.
Paris prosecutor Remy Heitz said Wednesday the preliminary conclusion is that there's no evidence the fire at the 850-year-old cathedral was deliberately set. A judicial inquiry has been looking for the cause of the fire, which destroyed the cathedral's roof and iconic spire on April 15.
Heitz said the investigation has so far found the most likely candidates are an electrical malfunction or a "badly stubbed out" cigarette. However, he added, authorities believe negligence may have been a root cause.
Investigators have so far interviewed more than 100 witness and have not singled out any individuals for responsibility.
Le Bras Freres, the scaffolding company working on the cathedral's renovation project, said after the blaze in April that some workers smoked at the Notre Dame site.
Nearly $1 billion in aid donations were received from around the world in the days after the fire. A French renovation expert said at the time repairs could as much as $2 billion.