The rendezvous that established Gov. Eliot Spitzer’s involvement with high-priced prostitutes occurred last month in one of Washington’s grandest hotels, but the criminal investigation that discovered the tryst began last year in a nondescript office building opposite a Dunkin’ Donuts on Long Island, according to law enforcement officials.
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Soon, the I.R.S. agents, from the agency’s Criminal Investigation Division, were working with F.B.I. agents and federal prosecutors from Manhattan who specialize in political corruption.
The inquiry, like many such investigations, was a delicate one. Because the focus was a high-ranking government official, prosecutors were required to seek the approval of the United States attorney general to proceed. Once they secured that permission, the investigation moved forward.