Premature insinuation is to give away or hint at something to early on, before you have the slightest proof or even know that what you are insinuating is the slightest bit true.
Detective Walsh: Virgo wasn't the one backing the money, now was he?
Suspect: What money....? Virgo is my dog...
Comissioner Tetley: Walsh, you need to get that premature insinuation of yours on a lock.