You are very right about the circumstantial evidence analogy. But when CBI says it, it sounds believable because they have access to all the investigations and evidences, when you say it with so much conviction that 'he definitely must be involved in killing his daughter'- you sound like .... (well you guessed it by now - a speculative and peanut brained moron who has arrived at this conclusion by an investigative logics developed by following the 3rd rate crime thrillers).
