Hi Trooper_D,
what I could gather in a quick internet search is the following:
The MIRS (Military Intelligence Service) was a joint Anglo-American agency with offices in Washington DC and London (Victoria Hotel), founded in May (other sources say January) 1943 under the supervision of Britain´s MI14 (Order of Battle German Forces) and the State´s G-2 (Assistent Chief of Staff). Shortly before the joint landing of British and US forces in North Africa. Its personnel was comprised mainly of German emmigrants to the US, its task was the analysis of captured German documents (150ts until 1945) and the dissemination of the knowledge gained through this. They had field agents who, especially directly after Germany´s surrender, discovered valuble documents in Germany that helped the allies prepare for the Nürnberg trials.
GreyC
Source e.g.: Germany and the 2nd WW, p. 306; Vol IX/II, Oxford 2014.