Does this pattern have the same meaning as the one explained here: とまではいかないまでも meaning?
I think it is different from the explanation linkend above. The linked example ‘includes’ statement A and B as true, while here statement A (犯人) is ’excluded’ while statement B (尋問できる) is ‘included’ as property/"feature" of 「お姉ちゃん」 (Translated along the lines of "not going as far as to say that something/someone/etc. is X but something/someone/etc. (obviously) is Y ")
The speaker talks to a female prisoner that was caught in a mysterious incident (invoving around 50 deaths) within the prison. She herself is not the culprit in this but at the same time the only person that survived the incident...
(Preceding sentence: 「懲罰房東で生き残ったのは刑務所側からすればお姉ちゃだけで！」 Original "separation" of the sentence": 「犯人、とはいわないまでも、何があったのか、尋問できるのは、お姉ちゃん、だけだ！」)