http://query.nytimes.com/mem/archive-free/pdf?_r=1&res=9D00E2D7163DE43BBC4950DFB3668388669FDE
Then our own Civil War St. Louis has this information deemed reliable:
http://www.civilwarstlouis.com/History/jamesstegenevieve.htm
The "Ste Genevieve Fair Play" newspaper account published May 29 1873 is considered reliable and does not make the assertion it was one of the James.
Arthur McCoy who was involved in the Adair Train robbery is credited with being involved at Ste Gen. and likely one or both of the Youngers given info gleaned from that robbery.
John R