I think there should always be two or three witnesses, not just one. That’s what the Bible says. Just one witness is too likely to be mistaken or deliberately lying.
I’d consider physical evidence as a witness. For instance, if this guy was caught pawning her stuff or if his DNA was on her couch or whatever.
What if she invited him home, initiated sexual intercourse, then had regrets in the morning and called him out for raping her? It does happen, you know, despite what the shrieking fem-hags say.
-ccm