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Since they're running this from a Mac, I assume they're using some sort of remote desktop application, so you would focus your investigation on that machine, and not the Mac. The Mac is really just a "dumb" terminal in this application.
You can try having a recovery service look into this to see if they can restore. If you want to do this however, you must make a backup NOW - the longer the application is used after the trouble is discovered, the less chance you have of a recovery.
Note there are some tools on the market that claim to do this, but if you want the best chance of success you should hire a company to do this, like www.everythingaccess.com.