That was why it was extremely easy for Weiss continue hiding her presence and do her Investigation. And these people were stupid enough to have only a single guard in front of the room where they kept their treasures, so this made Weiss's task even easier.
She did not kill the guard and make him to faint with the use of any force. Instead of a brute force method like that, she simply used a potion with a special smell that made people to fell asleep. And while he was in the dreamland, Weiss was able to do her Investigation without any kind of disturbance.
And the result of her investigation was quite fascinating. It looked like these fake bandits had absolutely no fear regarding any kind of retaliation. They were only doing the bare minimum to hide their identity.
