The Justice Department's public integrity section, which is also leading the wider campaign finance investigation, brought the charges in the case.
Justice Department lawyers in the public integrity section have been reviewing the taped material for three months.
In the past, lawmakers accused of wrongdoing have routinely been investigated by the Justice Department's public integrity section.
"I would have gone to the public integrity section of the Department of Justice," he replied.
The public integrity section in the Justice Department handles such matters all the time - and far more serious cases of official corruption.
The inquiry is being conducted at the Justice Department's headquarters by its public integrity section, which investigates corruption cases.
He joined the public integrity section right after graduating from Columbia Law School.
The Justice Department's public integrity section is responsible for cases involving government corruption.
The public integrity section examines allegations of wrongdoing on the part of public officials.
At some point after that, they said, the case was transferred to the Justice Department's public integrity section in Washington.