You did the right thing except that 30 days is much too nice.

It would be one thing if they confessed immediately. "I was desperate." That's a very good reason, to be honest. If they confessed, I would have even have found it hard to throw them out.

But to lie. To claim they only took $30, "The fairies took the rest" or what?

I would have gone ballistic when they persisted in lying.

In my experience, once someone lies to your face when both you and they know they're lying, then all bets are off.