Where can I get Information on a Sheriff for Cherokee Nation in 1869?

You might try the Cherokee Heritage Center in Tahlequah, Oklahoma. According to their website they are the holding place for the Cherokee National Archives and the Cherokee Family Research Center either of which might have information about elected officials for the Cherokee Nation. Here is their website: Cherokee Heritage Center, and their contact form: Contact Us.

Best of luck!

You should definitely contact the Oklahoma Historical Society, Oklahoma Historical Society -- as they have quite a few records involving sheriffs for the Cherokee Nation in the 19th century.