Bruce,
Thank you so much for your detailed and helpful response. I do know that he died on August 15, 1863--two records give the same date, and Place of Death is given as Gratiot Street Prison. I will check Alton as well as newspaper archives.
We are fortunate to have the copy of the microfilm from the National Archives giving his handwritten testimony as to how he came to be arrested. I have those documents as jpegs in my computer if you would like for me to send them to you. Briefly, he was entrapped by two Union soldiers named William Keith and Thomas Clark posing as men who "had been with Price." They asked Darne if there were "any soldiers near of any kind." He responded that he didn't know but that he had "heard that some bushwhackers had passed Readsville...supposed to be Cole and Ramsey a few days ago" but he didn't see them. (Were Cole and Ramsey particularly "bad guys?")
They asked him for food and a by-road to get to "between Williamsburg and Danville." They also wanted a coat and to trade their mule for his. He did give them cold cornbread and meat and directions, but refused the trade and gave no coat.
He was arrested the next day for violating the oath that he took in Fulton in February of 1862, taken to Mexico, Mo. where he did have an attorney (that document is almost indecipherable due to the ink bleeding from one side of the page to the other). We also have a copy of Keith and Clark's sworn testimony. He was sent to Gratiot Street...we also have a copy of the equivalent of his "intake interview." He states that he had nine slaves, evidently refused to answer the question about being a southern sympathizer, and when asked "Do you sincerely desire to have the southern people put down in this war, and the authority of the U.S. Government over them restored?" his response was "I do not."
The document also states that he gave an unfavorable impression, was "not truthful," and "not candid." All documents are signed by Geo. W. Shinn...whom I have read was in charge of that prison.
Since you speculated a bit in your answer to me...I think he was fairly arrogant and singularly unrepentant in his interview and probably wasn't particularly well treated in the prison due to his attitude...but other than the tenor of his answers, I have no proof of that.
This forum has opened my eyes to the true "civil war" that existed in Missouri and George Darne personifies much of the turmoil.

Thanks again.

Linda Pehr