Nandini killed gujral because she know about the married of karan and tanya thats whay firsta fall he killed gujral to save bhoomi then he send karan to jail and now i think so she try to kill tanya and she is very clever she is acting all the time infront of her family so dont believe her and those person that karans know she is not nandini he see mihir in near of teris but the real murderer s NANDINIđĄ