Among the items the FBI seized from City Hall were documents related to Kaiser, which paid Pugh more than $100,000 for books. The company previously said that its purchase of Pugh’s books had nothing to do with its securing business with the city, which it has had for decades. On Wednesday, a spokesman said the company could not comment on any subpoenas it may have received in the case, but “will, of course, cooperate fully with investigations of this matter.”