Sorry to hear about that. I agree, it sucks that we have to lock up something that's out in the woods, but that's "the way of the world" today, I guess.
There's always that small percentage of people who will take anything that's not nailed down, and some of those will take things that
are nailed down. If they're poaching game or otherwise being dirtbags-in-the-woods, they probably don't want their picture taken, either.
I don't know where Mstan99999 was located, and he hasn't posted anything here for over a year, but this thread shows that security cases aren't a guarantee against theft of a cam: <
http://www.chasingame.com/forum/viewtopic.php?f=34&t=20782>
But a good case with a good padlock, and something to make sure the case stays where you put it, can make many thieves just move on in search of something that's easier to steal.
Besides maybe hiding one cam to "watch" a more obvious decoy cam, some of the guys here have suggested various labels to make a potential thief think twice about stealing a cam. A clear label with black text wouldn't be easily noticed until somebody was right in front of the cam, and then they'd see something like "YOU BETTER MAKE SURE YOU FIND
ALL OF THEM." Even if there's only one camera around, they'll be left wondering how many other cams got their picture, and where those cams might be.

You might consider putting your cam(s) up above eye level, too. That'll make more work for you to change the memory card (I have to carry around a folding ladder so I can reach some of my cams), but if thief doesn't even notice a cam, that's good. If the cam is where he can't get his grubby mitts on it, that's even better.
Hope you have better luck with any other/future setups.