This article comprises two sections - I. The State of the Case, by Lucy Sussex, and II. The Pattern of Internal Evidence, by John Burrows. Part I discusses the historical and bibliographical evidence of authorship of the two crime series, 'Memoirs of an Australian Police Officer' and 'Adventures of an Australian Mounted Trooper', first published in The Australian Journal in the 1860s. Part II reports on a computer analysis of selected stories from these series and puts forward evidence relating to the authorship of these stories by Mary Fortune, possible collaboration between Fortune and James Skipp Borlase, and alleged plagiarism by Borlase. The analysis of results is accompanied by detailed tables and graphs.