So let me get this straight... You just had a wallet sitting on a dev server running test code with $100k on it?
There is no possible way you could be that stupid. Why on EARTH would you EVER store you wallet on there? Thats just beyond dumb..... You also kept unencrypted backups? I just cant comprehend this. I have very few bitcoin all stored in offline computers. It just makes no sense.
Maybe he/they were developing an app that used and transacted bitcoins, and that was their hot wallet.