Here comes the Notre Dame fire investigation

It's been more than a week since the Notre Dame cathedral caught fire, and French investigators said they have yet to rule out any potential causes of the blaze, Reuters reports.

• "Investigators are expected to search through the fire-damaged cathedral for remains of cables, lights or parts of circuitry that might give clues," The Guardian reports.

The big picture: Several potential causes still linger — electrical lifts from the outside of the building, electrical wiring on the inside and cigarette butts found inside. Officials believe the cause was possibly a short circuit linked to renovation.

Institutions connected to the possible causes deny being responsible:

• The scaffolding company that worked on the roof says the lifts were well maintained.
• The cathedral's spokesperson says the electrical wiring was properly installed, per Reuters.
• Construction company Le Bras Freres confirmed its workers smoked cigarettes at the construction site, but deemed that cause impossible, its spokesperson told AP.

Go deeper:

• Notre Dame blaze delivers cautionary tale
• Notre Dame fire: Pledges to help rebuild cathedral tops more than $1 billion