Hi, Debbie!
Personally, I don't know of Wirz ever visiting Millen, but it's certainly possible. Millen was only in operation for two months - October and November, 1864, so
@General Casey is right, knowing when the man was reportedly killed would help to determine the story's validity.
I'm also inclined to think that it's probably an error on the part of whoever compiled the database. Wirz had been shot in the arm/shoulder at the Battle of Seven Pines and had limited use of his right arm, which makes me think that the accounts of him beating prisoners to death are exaggerated. An awful lot of lies were told at his trial. Ex-park Ranger Jennifer thinks he pistol whipped a prisoner to death at one point, based on trial testimony, but I am not so sure.
Who's the man who died? And on what date? Knowing that will help. I know that Wirz was at Andersonville in October because multiple prisoners mentioned encountering him as they were leaving. I'm not so sure about the November guys. (Millen was only in operation in October and November, 1864.)
(For those who don't know,
@debwallsmith is probably the leading expert on the POW camp at Millen and helped to excavate the site of the prison several years ago. She is also in the process of compiling a database of all known prisoners who were held there, so if you know of any, you can let her know in this thread!)
Cheers!
Gary