Assassination Trivia

[Eva Elisabeth]

Hint #1: The image I used came from a book on the assassination of Lincoln. The author's last name is composed of 6 letters.

I found the letter in "The Web of Conspiracy" as the "Jorgen letter". I know "Jorgen" (respectively "Jørgen") mainly as a (Scandinavian) first name (alias "George", the German version is "Jürgen") , so if there's a different last name to figure I cannot find it in this book.

I think he meant Theodore Roscoe's last name.

...the letter was signed Roscoe??? (Please see Roger's initial question!)