I just recruited a party of three adventurers, equipped them all with horses, and then sent my sovereign to join them.  Instead of joining their party, she fought a battle on their square against an adventurer who I *hadn't* recruited, and who I don't think was even visible until the battle appeared.  When she won, the game declared me a murderer.

Aside from the obvious UI bugs, I think you should get a confirmation before an unprovoked attack, since it's pretty easy to click the wrong tile by accident.  Doubly important if there are gameplay consequences to being a "murderer", as the message seems to imply there should be.

I tried to reproduce this from my autosave and failed.