I found one train robbery in 1910, I don't know if this is the one you're looking for but it's the only one I could find. It was in Glencoe, St Louis County Missouri. St Louis Co is next to Jefferson Co. Not a lot of info but maybe you can research it more...http://www.rollanet.org/~conorw/cwome/glencoe-from_the_begin...
The Great Glencoe Train Robbery. Accounts are found in two books in the Missouri Historical Society collection: A Review of Famous Crimes Solved by St. Louis Policemen and Fifty Years a Detective, the latter by a "private eye" of that era.
Two masked and armed men, one with his hand in a bandage, boarded the passenger train No. 8 at a water tank near Eureka. This occurred on either January 21st or February 21, 1910 (depending on which book one believes.) Hidden between the tender and the mail car, the armed desperadoes took over the locomotive at Glencoe, fired a fusillade of shots at the conductor and curious passengers, disconnected locomotive, tender and mail car from the rest of the train and, with engineer and fireman under gunpoint, piloted the steam locomotive down the tracks a mile or two.
There they gathered up the mail sacks of registered mail, rifled some until they had $600 in cash, then, releasing the engineer and fireman (who steamed hastily back to Glencoe) they stashed the remaining registered mail sacks amidst corn shock in a field, boarded a hidden rowboat and escaped down the Meramec.
Depending upon which account is read, diligent work by the private detective, or by the St. Louis police, led to the apprehension of both culprits. George Ebberling was taken in Hot. Springs, Arkansas, where he was "taking the baths. "William W. Lowe, identified by the boils on his right hand which had required the bandage and forced him to shoot left-handed, was arrested in his bogus brokerage office in downtown St. Louis. The registered mail sacks were retrieved from the corn shocks and both men were sent up the river to the penitentiary at Jefferson City.
Good luck with your search!!