I suspect the hearings that are referred to here were the war-time hearings into the militia by the Missouri General Assembly. The resulting report was entitled as follows--"Report of the Committee of the House of Representatives of the Twenty-Second General Assembly of the State of Missouri, Appointed to Investigate the Conduct and Management of the Militia" (Jefferson City, Mo.: W.A. Curry, Public Printer, 1864). This was not an investigation of the EMM/PEMM etc. as much as it was a manifestation of the ongoing conflict and mudslinging going on between the Radical Unionist and Conservative Unionist factions. Be that as it may, the report has turned out to be an excellent historical resource. The Radicals controlled the state post-war, so it is not likely they would have undertaken an investigation into the wartime actions of Radicals.... In any event, a somewhat unwieldy-to-use online reprint of the 1864 "Report of the Committee" can be found here--