That's a very important point -- and it deserves to be highlighted, echoed, and underscored!! Indexes are powerful time-savers, but they are by no means infallible. If it's someone you really want or need to find, it's well worth your time to slog through the original record. Moreover, the original document may also yield clues or serendipitous finds that you'll (almost) never achieve through index surfing.
Often names are transcribed incorrectly!