As you likely know Fred, Joseph Pratte the senior was one of the largest slave owners in Perry County antebellum with 16 slaves listed on the Perry County tax roles. He and his son Peter R ran a dry goods store in Perryville. Pratte's wife was Mary Valle a long standing and respected family name in the Ste Gen, Perry Co, Madison Co area. I have Joseph Pratte the elder dead in 1847. Peter Rosamund Pratte, the son continued with the store and married Louise Beauvais.He died in 1853. Thus the Joseph Pratte you list must be a grandson of the elder. Following that we do find that Peter R had a son Joseph Pratte who married Henrietta Burns. Peter R also had a brother Bernard who married 3 times and had a son Joseph by his second wife Jane Coffman, daughter of Col. Joseph Coffman. This Joseph died unmarried.

So we are chasing 2 likely candidates. But I wonder if this was a post war vigilante hit by former members of 2nd MO MSM.

Bernard's son was born 1843 per the 1860 census:

Name: Joseph Pratte
Age: 17
Birth Year: abt 1843
Gender: Male
Birth Place: Missouri
Home in 1860: St Mary, Sainte Genevieve, Missouri
Post Office: St Mary
Dwelling Number: 1266
Family Number: 1260
Occupation: Pupil
Real Estate Value: 3500
Personal Estate Value: 2000
Attended School: Y
Household Members Age
Bernard S Pratte 51
Ann Pratte 36
Mary Pratte 18
Joseph Pratte 17
Bernard S Pratte
Jane Pratte 10
Peter R Pratte 5
Ella Pratte 1

JJR