Swamped

The only thing you find is a small jar filled with beetles.

It's not a clue to the thief, per se - it's just the one thing they didn't steal. You remember Doc told you about these - even kept some. There's a lot of tiny creatures that like to live in people's skin and these beetles have a taste for most of them. Of course, most people don't like to have beetles crawling around on them, so other remedies have been found over the years, but apparently there's a few where these beetles are still the best option, even in your own time. Or at least, the best option available to Marshguards.

Everything else in the lockbox is gone. Maybe the thief didn't like bugs?

Or they were looking for something in particular, and the beetles were the only thing they were sure wasn't it. Well, that doesn't help you much, does it?

Just as you're about to put the jar down, though, you notice that the beetles are moving in strange patterns...

Oh hells. This again. They're making letters. As if you didn't have enough problems without the gods poking their noses into it.

You don't feel much better about it after reading the message, either.