Which of the guests does Macarthur think are innocent of the crimes the voice on the gramophone accuses them of committing?

After hearing the accusations on the gramophone, Macarthur notes that he doesn't believe either Emily Brent or Vera Claythorne to be guilty of the crimes they've been accused of.

Surely nobody could have taken the accusation seriously. There had been a pack of other nonsense, just as far-fetched. That charming girl - the voice had accused her of drowning a child! Idiotic! Some madman throwing crazy accusations about!

Emily Brent, too - actually a niece of old Tom Brent of the Regiment. It had accused her of murder! Any one could see with half an eye that the woman was as pious as could be - the kind that was hand and glove with parsons.