Im guessing either Takash or Rawers killed the other. They used Arsenic in the salad which would explain the blood and it only being half eaten. Then drug the body to the stage when no one was nearby.And then went into hiding which would explain why no one can find either of them
"How can you not tell?"
"Im sorry, but everyone's faces have so little detail, we can only tel whos who by thier hair and clothing"