Anyone have any good idea of how these work yet?
I actually had one of these pop up in my current fort. One of my artifacts vanished, with no idea of who took it, and it showed up on my Justice screen as "theft." Selecting it, I had the option of interrogating various people (and animals...) for info. I did try having some interrogated to see if I could get any info, but some knew nothing, and some refused to cooperate (because the sheriff apparently misjudged their character, giving us some reason I guess to pay more attention to sheriff traits as far as... some sort of social skill(s) anyhow).
I then had a second artifact that was stolen about a year later maybe, but this time someone saw the transaction taking place. One my my dwarfs (one of my nobles in fact, my bookkeeper) was handing off a second artifact to a human non-resident guest. Even though the human was a non-resident I was able to punish them both for the theft. I then interrogated the bookkeeper on that first unsolved theft, and "for the love of" the interrogator (the sheriff, both of them from the starting seven) she confessed to a plot to steal that first artifact after being corrupted by the same human as stole the second one. I them punished the bookkeeper for the theft and finally closed the case, because I couldn't seem to punish the non-resident guest who started the trouble and actually ended up with the artifacts.
So now I actually have counterintelligence popping up for the conspiracy (!), but I'm not sure what (if anything) can be done with it. I mean it's intriguing and interesting to look at it, but I'm not sure if I can then use the info to do anything. I'm especially interested because it looks like there are more plots involved there, one of which I assume is probably the second artifact theft. I'd LIKE to get my two artifacts back, but the only possible way I can think of to do it is to just have my military dwarfs kill the human, to see if he still has them on him, but I'm worried about causing more trouble in the long run if I do that in case it ticks off the human civilization/causes loyalty issues (which I already have enough problem with stressed dwarfs), or whatever.
In case anyone's interested here are some images of some of the counterintelligence and so on. Forgive me if this is old news - I THINK it was added in this version (well, .01), and couldn't find info in the wiki, but I could of course be wrong.