inside the dark maze at the end of a hall I saw a npc model with a translucent blue material, when zooming in with the crossbow it disappeared (or turned black) and when I got close to it and it turned black then disappeared, it was a multiplayer game but no one there could've probably faked it or was even near me to fake it (besides I would probably hear toolgun noises)

if anyone has any similar experience, please tell.