If we cannot determine the probability of the story, then it cannot be shown that the story is likely to be true, but neither can it be shown that the story is unlikely to be true.
There is, however, one final possibility that needs to be considered. This is the idea that what is needed in a defense is not a story that can be shown to be likely to be true, but, rather, a story that, for all we know, is not unlikely. The thought here is that, even if there is some probability that the story has relative to our evidential base, we may not be able to determine what that probability is, or even any reasonably delimited range in which that probability falls. If so, it cannot be shown that the story is likely to be true, but neither can it be shown that the story is unlikely...