I don't know if this is the same thing, I think it is because I remember the 100 interviews (actually, I thought it was 100 people interviewed, which might not be the same thing), but I read recently of an investigation into 2,000 FISA warrants. Sounds like a bit of work to me.
From the article...
Another possible reason for the long classification review of Horowitz's report by the DOJ and the FBI is its length. In his letter to Congress last month announcing the completion of his investigation, Horowitz said his "team has reviewed over one million records and conducted over 100 interviews." He also offered some insight into why his inquiry took longer than expected, noting that several witnesses "only recently agreed to be interviewed."