Jim, you might pull out three books to analyze one possibility of what may have happened--
1) "Lost Family--Lost Cause" by Ivan McKee p. 68, 70
2) "The Civil War Reminiscences of General M. Jeff Thompson" edited by Stanton, Berquist and Bowers pp. 287-288
3) "Autobiography of Samuel S. Hildebrand" edited by Kirby Ross (refer to index entries regarding McGees)

In the Hildebrand book, I lay out in a fair amount of detail the tit-for-tat going on between Union supporters and the followers of Dan McGee. McKee does the same throughout his book. In his book, McKee discusses the killing of the men who were memorialized by the monument of which you refer. McKee also refers to a Joel Dennis who was going to be executed with the rest of the men, but "was able to convey the distress signal of a secret order to the commander and he was ordered to stand aside." McKee then goes on to discuss how Dennis had been documented as being a member of the Masonic Order.

Now go to the Jeff Thompson memoir. Thompson discusses how at the time of the surrenders at Wittsburg and Jacksonport, Confederates who had been involved in tit-for-tat warfare came into his hands. Thompson spoke about how the spill-over effect was causing a lot of collateral damage to innocents and that as long as these Confederates were alive, that spillover was going to continue. Thompson, not being able to deal with the Union side of the tit-for-tat problem without continuing to wage war against the North, decided to deal with the side of the problem that he could without continuing to fight the war. Thompson coldly admitted that his plan to deal with the Confederates was "of the most violent nature." In the midst of the Wittsburg and Jacksonport surrenders, Thompson describes how he went to a local Masonic Order and enlisted them in his plan, and how, with their support, he went on to execute the Confederates in his hands.

We can analyze this thing forever, but we are never going to know for sure. I do know one thing--if I am a Mason in northeast Arkansas doing General Jeff Thompson's bidding, and I take part in a firing squad to kill Confederates whose crime was nothing more than to go tit-for-tat with some bad folks back up in Missouri, then I am going to try to draw attention away from myself and on to the common enemy -- Federal troops. How do you do that? You dress up like one, and then send a sole survivor back home with to say the Yankees done it.

Whether this is what happened to the subjects of the memorial in the Cowan Cemetery, I don't know. What I do know is that Jeff Thompson surely admitted to doing something that connects up real closely to what happened to those boys who were memorialized by that monument.