Not sure if you have searched the internet much but here are some things I have found.
On 22 May 1945, US Army Special Mission V-2 shipped the first trainload of rocket parts for use in projects such as Operation Sandy, Operation Blossom and, at the White Sands Proving Grounds, the Hermes project. The Nordhausen area was to become part of the Soviet zone of occupation, and Soviet Army officers arrived to tour the Nordhausen plant on 26 May 1945. In June 1945, the US Army left the Nordhausen plant as required by JCS Directive 1067/14, with parts, machine tools, and documents (including blueprints for the projected A-9/A-10 intercontinental missile) left for the Soviets. The Red Army occupied the Mittelwerk on 5 July 1945 and demolished both of the entrances of the tunnel system in mid-1948.
Elliot, yes, I have been reading about operation Special Mission V-2 led by Colonel Toftoy and Major Hamill to Nordhausen/Dora/Mittelwerk. But a source told me my father, assigned to the 54th Ordnance Technical Intelligence Team as a driver/interpreter/combat-experienced infantryman (T-Force?), claims (1) he went to Peenemunde where he saw/collected rocket parts, and (2) was "exposed" to radiation. My current thought is my father confused Nordhausen over time with Peenemunde; prior to his death, he couldn't recall the names of the towns nor battles he fought going over the Voges Mountains with the 36th Infantry Division. The radiation comment probably was related to either the Nordhausen vicinity dig, or the ALSOS mission to dismantle the nuclear reactor in Haigerloch and retrieve its uranium. I can't find a shred of evidence of any "sneaking" into Peenemunde; perhaps the OSS?
Dear Mr. Reich,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located 8 series and 125 file units in various record groups that include records of the “12th Army Group” and “G-2” during the 1940s, expecially the G-2 reports and journals such as the Periodic Reports and Intelligence Reports and Summaries. We also located 3 series and 43 file units in various record groups that include any records on the “6th Army Group” and “G-2” during WWII, especially the Intelligence Reports and Summaries. For access to these records, please contact the reference unit listed in the record descriptions.
In addition, we located the World War II Operations Reports, 1940-1948 in the Records of the Adjutant General's Office, 1917-1985 (Record Group 407) that includes records of the 6th and 12th Army Groups. For access to and/or copies of this/these records, please contact the National Archives at College Park - Textual Reference (RDT2) via email at firstname.lastname@example.org.
Next, we located 5 series & 5 file units mostly in the Records of Allied Operational and Occupation Headquarters, World War II (Record Group 331) that relate to “Target Force” during WWII. Plus, we located the series titled Intelligence and Investigative Dossiers Impersonal Files, ca. 1977 ca. 2004 in the Records of the Army Staff (Record Group 319) that includes three file units pertaining to “rockets.” For access to these records, please contact RDT2.
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We hope this is helpful. Best of luck with your research!