Operation Snow White was a criminal conspiracy by the Church of Scientology during the 1970s to purge unfavorable records about Scientology and its founder, L. Ron Hubbard. This project included a series of infiltrations into and thefts from 136 government agencies, foreign embassies and consulates, as well as private organizations critical of Scientology, carried out by Church members in more than 30 countries.
It was various offices but mainly the IRS:
https://en.wikipedia.org/wiki/Operation_Snow_White