Dear Bindu Madhavi,
As stated by Mr Nair, you can recover the losses caused by the contractor or their staff. However, before doing this, I recommend you order the domestic enquiry. Let the culpability of the theft be established clearly. You cannot recover the losses on the grounds of "suspicion".
When the enquiry is ordered, send the formal letter to the contractor about the initiation of the enquiry. This will set the ground for your future correspondence.
Check the contract agreement with the contractor and find out whether any clause exists on the recovery of the losses.
Secondly, domestic enquiry should be conducted to investigate the lapses in the existing system. The focus of the enquiry should be on the system and not on the person. Your goal is not just to recover the money but to avoid the theft cases in future too.
Many times the theft cases happen because the proper records are not maintained or the security processes are inadequate. If the adequate controls are not established then theft cases are bound to happen. Therefore, after the enquiry, what remedial action needs to be taken that also you should think.
Thanks,
Dinesh Divekar