What is another word for prolonged interrogation?
Pronunciation: [pɹəlˈɒŋd ɪntˌɛɹəɡˈe͡ɪʃən] (IPA) 
There are several synonyms for the phrase "prolonged interrogation," each with slightly different connotations. One is "extended questioning," which implies that the interrogation lasted for a significant amount of time. Another is "sustained interrogation," which suggests that the questioning was intense and potentially grueling. "Persistent questioning" implies that the interrogator was unrelenting in their attempts to obtain information, whereas "protracted interrogation" emphasizes the length of time involved. Finally, "lengthy interrogation" simply conveys that the questioning went on for a substantial amount of time, with no other specific connotations.
