'Nightline' Investigated Sen. John Ensign's Alleged Affair With Staffer in 2009

May 13, 2011— -- The Senate Ethics Committee on Thursday released the results of its 22-month investigation on former Sen. John Ensign's, R-Nev., alleged affair with a former staffer, Cynthia Hampton.

Hampton was the wife of Ensign's former best friend and chief of staff, Doug Hampton. Ensign resigned May 3, 2011, a day before the Ethics Committee was set to take action against him.

The Ethics Committee has now referred Ensign's case to the Justice Department and Ensign faces possible criminal charges. Read the full report.

Many of the details of Ensign's behavior and allegations of illegal activity, including information about how the alleged affair was discovered, the role of Sen. Tom Coburn, R-Okla., the so-called "C Street house" and allegations that Ensign violated campaign finance laws, were reported in a special investigation by "Nightline's" Cynthia McFadden that aired on Nov. 23, 2009.

"Nightline's" November 2009 investigation included the first national television interview with Ensign's main accuser, Doug Hampton. Hampton also accused Ensign of breaking federal ethics laws by knowingly assisting him in lobbying Ensign's office within a year of his working there.

At the time of the "Nightline" interview, Hampton said he had not been contacted by the Department of Justice or the Senate Ethics Committee, despite his very public claims against Ensign.

When asked what conclusion he drew from that, Hampton replied, "Not really interested in getting to the bottom of this. It's funny. When you're campaigning, boy, you have to talk about everything. When you're elected? You don't have to talk about anything."

Watch the full 2009 "Nightline" investigation and interview with Doug Hampton here.