The only way to really know about the permitting of work done would be to go to the cities permitting department to determine if permits were pulled when the work was completed. Here is a link to City of Oakland's permitting department: http://www.oaklandnet.com/government/CEDA/revised/building_p
The only other way to know if the current owner is the one who completed the work.
I hope this helps!
Alain Pinel Realtors