Vacant Short Sale Listing - Who is Responsible?

I have several short sale listings.  A majority of them are occupied by the homeowner.  Occassionally I have sellers who are fed up with the process and wind up moving out prior to the short sale completion but they typically remain in the area and continue to check on the status of the property as we also do.  However, I currently have a short sale listing where the homeowner has moved on and out of the state completely.  After the home had been vacant for about a month the lender slapped a vacancy sticker on the window and changed the locks.  I immediately contacted the lender to inform them that I have a buyer in escrow ready to close the short sale transaction.  The bank sent me the key Fedex. 

After two buyers have walked during the purchase process the home has remained vacant and unfortunately vandalized several times.  Apparently the rear slider doors have been lifted out of the tracks and removed for easy access.  I believe that I resolve this security breach with each subsequent visit only to find another avenue discovered for entry.  The condition of the home is slowly disintegrating to the point that it is far more of a burden on me than an asset.  The particularly interesting aspect to this story is that Bank of America has never set a foreclosure date on the home.  It appears as if they do not want to take it back.  So I ask myself, who is ultimately on the hook for liability with regards to this home?