The Solomon W. Mathews you mentioned in the Bienville Parish documents was born in 1859 and was murdered in 1921. His wife was Mary Jane Stevens, his children: daughters Jessie, Minnie, Ruby and Bertha; one son, Lewis (possibly spelled Louis or Louie) Mathews. Solomon is buried at Pleasant Grove Cemetery in Ringgold, Bienville Parish, Louisiana. Surrounding parishes (counties) of Bienville are Claiborne, Red River, Natchitoches and Jackson. Through newspaper articles about his murder (for his money), it was mentioned he owned property in Red River Parish, where his murderers came lived. It seems to me that the 1870 Solomon Mathews could definitely be the same one.