my companion and I got separated in a fight near my camp.
When I came back to camp I found a bandit there, killed by my companion. On the bandit I found an item previously stored in my chest, a Vampiric Staff.
Somehow the bandit accessed my chest and took the most powerful weapon stored there. She was in a pretty bad shape already when I got separated from my companion, maybe she felt she needed better gear to survive.
Once I also saw bandits loot my corpse after I lost a fight.
If these are vanilla features which I think they are, this would IMHO open interesting modding possibilities.
Rgds, Haldir