Last night, I just walked out of Belethor's store (weapons sheathed) and a guard stopped me to ask:
You there, what do you know about this?
I had two options: "I don't know anything about it" or "I'm not telling you anything"
I selected the first option as I legitimately had no idea what I did and the guard said something along the lines of:
Okay, but I have my eye on you.
Immediately after he said this, he stopped me again and asked the same question
You there, what do you know about this?
and I replied with the other option:
I'm not telling you anything.
Well, he promptly threw me in jail. What did I do that would have caused this? I ended up reloading to the autosave from me walking out of Belethor's store and I was not stopped by any guard. I now had the chance to look around and there was only a vampire's body on the ground near the warmaiden's shop (a block or two away). This body has been there for at least 5 in-game days.
Was this a glitch or what would have triggered this guard from stopping me?
I did not have any bounty in Whiterun and I did not have any companion with me.