I believe the records for which you are searching can be found in Ft. Smith, AR. My reason is this: posted on website http://www.usgennet.org/usa/ok/county/atoka/index.htmlhttp://www.usgennet.org/usa/ok/county/atoka/index.html you will find a portion of the 1899? Indian Citizen Newspapers. I have been working on this newspaper for a few years, and still have much more to post.
The newspaper mentions a particular case that comes to mind of a gentleman name Hotema. He was charged with murder and the case was held in the Federal Court in Ft. Smith, Ar.