Pagliano — a potential key figure in the probe — declined to speak to the inspector general’s investigators, informing them through his Washington lawyer, Mark MacDougall, that he would invoke his Fifth Amendment right, the sources said.
Then, in late July, the State Department inspector general and the inspector general for the director of national intelligence referred the matter to the FBI counterintelligence division to determine if classified information was mishandled through the use of the private email server after finding evidence that classified information was communicated on emails sent through the server. But officials stressed at that time that the inquiry was an intelligence probe and not a criminal investigation.

At that point, the FBI also sought to question Pagliano and he again refused. His refusal to answer questions was communicated by his lawyer to senior lawyers in the counterintelligence section of the Justice Department’s national security division — one of whom had previously been in charge of the investigation into former CIA Director David Petraeus, the sources said.

MacDougall, Pagliano’s lawyer, declined any comment, and sources note that is not uncommon for lawyers with clients in sensitive investigations to invoke their Fifth Amendment right against self-incrimination. Even if their clients are not the targets of the investigation, lawyers argue that the clients could be confronted with documents or questions they are not prepared for and inadvertently subject themselves to charges that they are not being truthful.