Some info verified using a DCM scan (http://digitalcomicmuseum.com/)
story continues in Blue Ribbon Comics (1939 series) #6 (September 1940); Penciller and inker credits corrected by Denys Howard on 20 July 2004 from information from Jerry Bails; original credit was "Johann Bulthuis"
The signature is JOHANN, not John, and it is the same artist according to Jerry Bails' Who's Who.
Originally credited Mort Meskin. Compared with his signed story in #6, this is not him, but George Storm. Compare also with Storm's story in Hangman #19, with long and lively inklines. He is credited on this feature by Jerry Bails' Who's Who.