Dear Mr. Manzano,
Thank you for posting your request on History Hub!
If you have not done so already, we suggest that you request a copy of Vincent Fast Horse’s Official Military Personnel File (OMPF). OMPFs and medical records of enlisted men of the U.S. Navy who were separated from the service after 1885 and before 1959 are located at NARA's National Personnel Records Center (NPRC), (Military Personnel Records), 1 Archives Drive, St. Louis, MO 63138-1002. To request these records, please mail a completed GSA Standard Form 180 to NPRC. Veterans and their next of kin also may use eVetRecs to request records. See eVetRecs Help for instructions. For more information see Official Military Personnel Files (OMPF), Archival Records Requests.
We searched the National Archives Catalog and located a reference to an individual named Vincent Fast Horse on page 4 of the State Summary of War Casualties from World War II for Navy, Marine Corps, and Coast Guard Personnel from South Dakota, which is part of the series State Summaries of War Casualties for the United States Navy, Marine Corps, and Coast Guard during World War II in the General Records of the Department of the Navy (Record Group 80). This file has been digitized and can be viewed online in the Catalog.
We also located the series World War II War Diaries, Other Operational Records and Histories in the Records of the Office of the Chief of Naval Operations (Record Group 38) that contains 56 files related to the USS Indianapolis. These files have been digitized and can be viewed online in the Catalog.
In addition, we located the series Records Relating to the Sinking of USS Indianapolis in the Records of the Bureau of Navy Personnel (Record Group 24) and the series World War II Oral Histories, Interviews and Statements in Record Group 38, which includes a transcription of an interview with Captain Charles B. McVay, commanding officer of the USS Indianapolis, given just a few weeks after the cruiser was sunk by a Japanese submarine in 1945 that may be of interest to you. These records have not been digitized. Please contact the National Archives at College Park - Textual Reference (RDT2) at firstname.lastname@example.org for access to and information about these and similar records.
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RDT2. Also, NPRC will continue servicing requests ONLY associated with medical treatments, burials, homeless veterans seeking admittance to a homeless shelter, and those involving the VA Home Loan program. If your request is urgent, please see Emergency Requests and Deadlines. Please refrain from submitting non-emergency requests such as replacement medals, administrative corrections, or records research until NPRC returns to pre-COVID staffing levels. Please check archives.gov/veterans for updates to the NPRC operating hours and status. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this information is helpful, and best of luck with your research!