I fear you're conflating our criminal and civil court systems.
In a criminal matter there is the requirement for the prosecution to adequetely prove guilt and otherwise there is a presumption of innocence. This is not however anything to do with this matter in hand - so far I understand Gregg...
Indeed, "I've met thousands and thousands of people over the last 20 years, and I've only brutally murdered 13 of them" would not form part of a winning trial defence...