'That was my wife.'
'Dead?' the boy asked.
Slowly the man shook his head. He pursed his lips as though about to whistle and answered in a long-drawn way: 'Nuuu—' he said. 'I will explain.'
Leo Rosten in The Joys of Yiddish lists nineteen different uses or shadings of "nu" (from the Russian, "well"). The eighteenth and nineteenth may be closest to McCullers' use above: "And so, in the course of time" & "One thing led to another, and …". Or even most simply, just "welll…."
He claims "nu" is the most used word in spoken Yiddish (after the articles and "oy"). It's so very Yiddish that a conversation might consist of "Nu?" followed by "Nu-nu." (meaning "Are you Jewish?" and "Yes.") Which raises—or as some people say, begs—the question, is the old guy Jewish? And beyond that is he "The Wandering Jew"?
I've reread the story with this question in mind, and although there are a few references to his big shnoz (a word which, by the way, does not occur in the story), I think "The Wandering Jew" is just one of many archetypes in the background of this character. Another is "The Ancient Mariner," mentioned during our discussion. But unlike either of these the man in the corner has not laughed at Jesus or killed an albatross. His "mistake" (hamartia) has been precipitateness. Like Koko (another character) he should have started small, hence the title.
A question I've got going begging, however, is whether Carson McCullers had ever heard this word before she arrived in NYC. Nuu—…?