When you indicate interrupted speech with an ellipsis (either three spaced periods or the single glyph), be aware of whether the next word needs to be capitalized.
If someone starts to speak, stops, then starts over with the same words, it's good to capitalize the repetition. They've gone back to the beginning. Treat their resumption of speech like a new sentence (which, arguably, it is).
If they're speaking, they stop, and continue on, don't capitalize the first word after the ellipsis (unless, of course, it's a proper noun).
"Are you . . . Are you my mother?"
"Are you . . . my mother?"