It means know one knows who they are now chasing, or at least the person talking has no idea who might know who they are chasing. In this case it is 'she' doesn't know who the 'fibbies' (I think that might be a derogatory name for the FBI) are chasing and she doesn't know who might know who they are chasing.
'Who knows where' is often used to indicate know one knows where
I hope that makes sense, I've just read it and it's a bit gobbledygooky
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