I dont know why Police and CBI are struggling while the logic is so easy.
1. Nobody has come forward and confessed.(So the person doesn't want to accept the guilt) 2.Nothing was stolen from home(Except for mobile phones!Which again indicates that the motive of the culprit is to hide) 3.The colony where the house is located has 3 tire security.So somebody new entering would have come to attention easily 4.The murder didnt happen day time(Which can raise the suspicion of outsider murdering for rage/relationship/money etc) 5.Hemraj was killed without any fight and Arushi was also killed without much fight.( So somebody whom they knew should have surprised them by killing them suddenly by slashing their necks) 6.Family members were at home when it occured!Raises high level of suspicion in a high security facility! 7. As a doctor parent of a girl killed, you will not rush to cremate your girl as the families will focus on finding the culprit,but parents are not showing any concern but hiding their guilt 8.Hemraj's body was hidden on terrace(If an outsider killed, he doesnt have to hide)
Further mother's lack of concern about the daugther's death, as watched by everybody on TV
So the conclusion is that there is high suspicion on parents,who were present at home, have skills, possible tendency to hide phones, body of the servant and trying to wash the blood with minimal concern
Doing Narco/Brain mapping may be helpful and CBI should focus on finding the motive.
