Publication of the original German series in a biweekly Dutch translation started in 1910 (Source: Lord Listerklub). The original series was followed by 16 issues (or 15, the Lord Listerklub lists #119 as "never seen yet") by an unknown author, in which many of the stories were situated in the Netherlands. From June 14, 1923, the first issue, "De Onbekende", appeared as a feuilleton in the newspaper Rotterdamsch Nieuwsblad. Starting with #127 the stories were written by Felix Hageman as an uncredited author. Starting with #514 more or less updated and renamed reprints of Dutch and German stories appeared in the series, mixed with new stories. The last new stories were published in the early 1930s.
