This is how it works. If you are going to make an allegation against someone, you have to be quite specific. It won't do, for example, to just say "I accuse you of murdering someone" and then when asked for more detail become all coy and mysterious. Because if you do that, you are going to be laughed out of court and then most likely face charges yourself. It's far better to get your facts straight from the outset. You know the sort of thing, carry out some basic investigation, check your facts and gather evidence. Otherwise, you end up looking pretty stupid.