You're very welcome. I saw your other note--checked my disk of Conf. prisoner death records and there he was, but misspelled so he hadn't come up right away when I first looked. Scanned through Johnson's Island and found him:
John Kitchain, Phelps Co., died Dec. 23, 1862, see note.
The note says, "Reported as having died on Johnson's Island, but the grave was not located. A number of graves in the Confederate Cemetery are marked as 'Unknown,' and it is thought they are graves of these particular dead, as the number not identified is practically the same as the number of graves marked unknown."
There's several places you can go for more info on him. One is the National Archives in the Provost Marshal records for individual citizens (as he was not officially considered a Confederate soldier he'd fall in this catagory as did many classed as bushwhackers). It would be in microfilm series M345 with the rolls listed alphabetically. You can see the listing of microfilm rolls at: http://merrimack.nara.gov/publications/microfilm/biographica...
He should be on roll 154 but you have the potential spelling problem that could put him on the next roll or even split the info between the two. It's somewhat a gamble how much info is in these rolls on an individual. The Missouri records are the most complete but it still could range from a great deal of info to little to none. I'd suspect he'd fall somewhere in between. You can purchase the rolls right from NARA or possibly query them to pay someone there to search the rolls and copy the info.
Another place to get some info might be St. Louis newspapers (now that you have dates) with info on Gratiot arrival/departures listed daily. You can query the St. Louis Public Library about that (there's a link to that and NARA, and other things, on my website under "links"). He's probably in Johnson's Island records too at NARA. Those would fall under microfilm series M598. You can see a breakdown of those rolls at: http://merrimack.nara.gov/publications/microfilm/military/mi...
Or a web search may lead you to someone who's working on Johnson's Island like I'm working on Gratiot ;-)