The discussion of David Guitar rang a bell, so I checked the records of the Adjutant General for the 61st Regiment. Below is the text of a letter, dated February 25, 1863, from Col. J.B. Douglass, Headquarter 61st Regiment EMM, Columbia, to W.D. Ward, A.A. General, St. Louis:

Sir Enclosed I send you Roster of the 61st Regiment EMM, in obedience to Orders No. 7 issued from your Headquarters 19th inst. You will perceive that four companies of my Regiment are marked as Disloyal; yet the Captains of all of them enrolled as loyal, but as a considerable portion of the men in each of their companies were regarded at one time as Disloyal I have so placed them; and in making selections among the different companies in my Regiment I selected those companies that were of undoubted loyalty for active duty.

From Douglass's list, showing only those companies listed as disloyal:
B, David Guitar, not in active service "Disloyal"
D, Jas M Ellis, not inactive service "Disloyal"
I, Joseph I Sterne, not in active service "Disloyal"
K, Jno W Rollins, not in active service "Disloyal"