I have got it...The Killer/Mystery Man has to be Kartik...Think about it...It is possible that since Angad is so famous - Kartik can be jealous. He was never a good guy to begin with in the beginning of the show. This might just prove us all right. He might be in love with Kanan..Wants the company to himself so he wants to remove all the road blocks in his way - Angad, Kripa & Nishant.
What do you think?