| dtewi said:
Sciuntne quem qui ab vulgo captus erat. But "quem qui" sounds stupid. |
Again, I'm very rusty, but I'd say that you use the interrogative pronoun when you're interrogating for the identity of the antecedent. As in
"Cuius liber est hic?"
In your case the interrogative is about the truth of "them" knowing about the identity of someone. You're asking "do they know [the person]" (doubt about knowledge) and not "whom do they know" (doubt about the object of knowledge). The fact that [the person] is actually the antecedent in a different (relative subordinate?) sentence is tangential, I think.
PS: Note that I might have mis-used terms regarding grammatical and sentence analysis commonly used in English, as I'm translating quite freely from Italian and I don't really master the appropriate lexicon. I hope you'll understand anyway :)
