2,215. A Zonah Out of Doubt

Hilchos Issurei Biah 18:15

If we know that a woman was intimate in a city or became pregnant in a city, then even if there’s only one non-Jew, chalal, servant, etc. living in that city, the preferred course of action is for her not to marry a kohein. This is because when things are in their fixed location, cases of doubt are treated as if the odds are 50/50. If she's already married to a kohein, they need not be separated because she says that she was intimate with someone who is halachically fit.

Hilchos Issurei Biah 18:16

If a woman can’t speak, can’t hear, if she says that she doesn’t know the identity of the man with whom she was intimate or if she was a minor who can’t distinguish between those who are halachically fit and those who aren’t, she is considered a zonah out of doubt. If she married a kohein, she must be divorced unless there’s the aforementioned double majority of halachically fit men with whom she could have been intimate.