 Over the years, historians and contemporary newspapers variously spelled O'Kelley's surname as "Kelly" or "O'Kelly", sometimes mistakenly using the letter "O" as his middle initial.Little is known of O'Kelley's youth, although his birthplace is reported as Harrisonville, Missouri.His mother was Margaret Ann Capehart (6 July 1836 – 27 July 1903), but at the time of her 14 July 1857 marriage to Dr. Thomas Katlett O'Kelley (20 October 1833 – 9 October 1923) she was already pregnant with Edward.