I dont know when seeing things unfolded i am seeing such a scenario that arushi may have been hit with the rod in the terrace and when they had doubts abt her recovery would have slit the throat in her bed room.(A wild imaginative guess.CBI says they have proof that her bed room door was opened when she was killed)may be she would have heard something mysterious in the terrace so would have gone to check wats it ( any curious teenager would do) the criminals would have been baffled to see her and would have hit her with the same weapon used to kill hemraj.throat slitting is a process done later to make it look professional.
