So... I had a run which I recruited two survivor into my group. I made sure there were water, food, and barricade in our base. Then one day after I return from a looting run, I saw one of the survivor missing and one is in the base.

By using the GUI, I tell the one missing to return to base, then I saw there's a option for the one in base to "Relax". I clicked it, and I DID NOT dismiss him. He suddenly turned hostile. I was like, wait a minute... Then he stab me from behind with a spear and killed me. I was furious.

After a quick search on internet, I don't find anything about NPC betrays players, some even says once they are in your group, they won't turn into raider. So is this a feature? Or just a bug?