California wine region fire cause may go undetected

California wine country's wildfires have largely been
brought under control but their cause may never be learned,
according to one key regulator.
Public utilities regulator Michael Picker said investigators may
not be able to find enough evidence to determine the cause,
including whether sparks from downed power lines operated by
Pacific Gas & Electric led to the catastrophic fire storm.
The San Francisco-based power company has said it has about
$800mn in insurance against wildfire damage.