Former Oregon governor John Kitzhaber (D) (AP Photo/Gosia Wozniacka)

Internal Revenue Service agents have joined the FBI investigation into former Oregon Gov. John Kitzhaber (D), who resigned from office last week amid mounting inquiries into his fiancee, Cylvia Hayes.

IRS and FBI agents questioned Michael Jordan, director of Oregon’s Department of Administrative Services, at his home, The Oregonian reported. Jordan told the paper the agents asked about Hayes’s work for Demos, a New York-based nonprofit that advocates for an alternative economic measure, and about emails showing the governor had urged Jordan to hire someone connected to the nonprofit.

The following day, the same agents handed Jordan a subpoena for e-mail correspondence sent by Kitzhaber, Hayes and 15 other state employees. Later that day, Kitzhaber announced he would resign.

Once Kitzhaber was out of office, state employees entered the Department of Administrative Services to collect computers and electronics used by his staffers. Jordan said the state technicians told him they were there after discussions with U.S. Attorney Amanda Marshall’s office.

The Oregonian reported earlier that Hayes’s federal tax returns did not appear to show the income she made from her consulting business. Hayes has hired a criminal defense attorney, and she has refused to comment on her taxes.

Kitzhaber’s resignation came after the state attorney general opened an investigation into Hayes’s private work on state business, including her use of Mahonia Hall, the governor’s official residence, for meetings. Kitzhaber has also hired a defense attorney to respond to the investigations.

The Department of Administrative Services asked state police to open a criminal investigation last week into leaks of Kitzhaber’s personal e-mails. The e-mails, published by Willamette Week, showed Hayes’s plans to leverage her access to the governor’s office into paid contracts and speaking appearances. They also showed Kitzhaber was involved in trying to circumvent an ethics review of Hayes’s actions.

As pressure mounted on Kitzhaber earlier this month, his personal assistant asked the DAS to destroy some emails sent from his gmail address and stored in state archives. The manager who blocked Kitzhaber’s effort to destroy those e-mails, Michael Rodgers, was one of two officials placed on leave during a personnel investigation Jordan launched.

Jordan, a close ally of Kitzhaber’s and Hayes’s, told the Oregonian he had not placed the two managers on leave in connection with the leak investigation. He said he was concerned about computer security, and that he worried about potential evidence leaking while two separate criminal investigations were underway.