Unguarded items on the ground are per rules free to take.
Next time, store them somewhere or on someone.
But you know even the name of who took them. Did you ask him if he still has them?
And you can replay quests with an alt and transfer the items, that saved me already several times.

(Official denunciation is bad behaviour in most cases imho. If you have a complaint against a player, try to sort it out directly
or involve GMs.)
Also

I wish that people would stop comparing genocide with their daily little dramas. You're insulting the victims.