So close....
From St Charles Missouri: a Brief History, by James W Erwin, pg 106

"On their first scout, troops under Captain Henry Windmuller killed 2 civilians and wounded 2 others who were working peacefully on their farms. About a week later, Kreckel refused to send troops to ambush rebels reportedly camped on a farm owned by Henry Renoe because he feared it a "secesh trick". Two days later Windmuller led a patrol to the farm....ransacked the house... shot Renoe on the way back to Fulton."

https://books.google.com/books?id=cggmDwAAQBAJ&lpg=PA107&ots=5_MkX7t2D-&dq=dr%20john%20bruere%20msm&pg=PA106#v=onepage&q=dr%20john%20bruere%20msm&f=false

Of course I can't see a primary reference.