U.S. National Archives (Record Group 104, Entry 24B, Slidell Investigation into New Orleans Mint) Publique Deposited
National Archives entry description: TESTIMONY PERTAINING TO COMMISSIONER SLIDELL'S INVESTIGATION OF THE NEW ORLEANS BRANCH MINT. June 17-July 4, 1839. 1 legal size box. 4 in. One legal box containing documents of the investigation.
National Archives catalog record: https://catalog.archives.gov/id/566279. See also the National Archives & Records Administration numismatic finding aids at https://nnp.wustl.edu/library/archivedetail/538870.