What about karthik...

I think karthik is the murderer...Nd vo rao ko fasa rha h...Rao isn't involved at all...And as siddhant thinks that rao can't do this all without the help or command of kk...He started thinking that kk is also involved in this...May be karthik is misguiding siddhant...

Karthik marvata PB ko i don't think ki booklet ko PB ke ghr pe chod deta vo.

No Karthik is NOT the killer otherwise he would have been at least a little awkward with the Sinhas as he is no James Bond...

Kartik can be behind the plane sabotage but not behind the murder may be

Since some episodes kartik is more like a good boy than how he was shown before.