Marty,
I know that you said it's "not the way you do business" however, I would seriously consider filing a report with the appropriate authorities. You don't have to ask them to investigate and press charges but have the report on file. I'm sure you are thinking, why. The reason is you intent to dock the contractor's pay for the damages. If the contractor decides to take you to court over it (I doubt he will but I have seen stupider things done), having the vandalism on file with the authorities documenting the whens, whys, and wherefores will significantly help. The longer you wait, the more you give the contractor the wherewithall to claim it was not his crew but vandalism by others and, potentially, reach 'reasonable doubt' with a given set of your 'peers'.
BTW, I have followed this thread consistently without comment as there were plenty of others cheering you on but let me take this opportunity to say WELL DONE! I can only hope to have as nice a shop some day.
Chip Charnley