evidence, was produced--so as to have better grounds for assessing its credibility.

To use a commonplace example from detective stories, a witness claims to have seen someone murdered. A first basis for judging this is whether or not the allegedly murdered person is known to be still alive--if so, the claim is very implausible. If the person concerned has disappeared, then the claim that murder has taken place is compatible with what is known, so this provides a degree of plausibility, though relatively weak; finding the body would increase