Ehm, if in this specific case, if he was accused of murder, and the circumstances were equally shady, I very much would assume lying is a very distinct possibility.

Let's assume someone was found dead in his flat with a overdose or something like that...my suspicion radar would be all over the place.

I do not assume rape victims are lying in most cases.

But it IS a very grave charge.

And if men get accused of it while being innocent, it pretty much ruins their lives, too.
So it shouldn't be assumed that every rape accusation, always and ever will be true, too.