Hired by the rebellious White Glove member Mortimer to silence anyone who is suspected of having knowlege, or is plotting against his plans to return the society to cannibalism, this assassin ensure that his employer's plan's aren't interfered with, in turn kept successful in the long term. In order to prevent his employer's plans from being revealed to the authorities, the assassin has arranged for Chauncey to be assassinated during a meeting with the detective Jay Barnes (or Crusoe.)
The assassin can be seen in a small room below the steam room. He can be seen in this room by using the tclconsole command for a closer look. He can also be found on the Xbox by going through a wall which is to your right after you enter the room, after you cross the corner go straight and you will end up a shady area. You will see a room for a short while because you fall and end back up in the place you started. It is possible to get there too, by somehow making a leap of faith. If you talk to the assassin you will only "look" at him for a split second then going back to normal. This is because the assassin uses an empty voice type. If you kill him, Chauncey also dies.