Hunter and his wife were accused of having used over $250,000 in campaign funds for their own personal use, which included family meals, medical bills, vacations, school tuition and even flying the family's pet rabbit, Eggburt, across the country.
Last summer, Margaret Hunter agreed to a plea deal that required her to testify against her husband; the indictment also contained evidence of numerous extramarital affairs that the congressmen had.
Duncan Hunter, however, had maintained his innocence, but eventually agreed to a deal in order, he said, to spare his family, especially his children, from a public trial.
"Whatever my time in custody is, I will take that hit," Hunter told local TV station KUSI last month. "My only hope is that the judge does not sentence my wife to jail. I think my kids need a mom in the home."
In his resignation letter, submitted Tuesday to Democratic Gov. Gavin Newsom and House Speaker Nancy Pelosi, D-San Francisco, Hunter said he was most proud of his service on the House Armed Services Committee during his tenure. Hunter joined the Marine Corps after the 9/11 terrorist attacks and served in Iraq and Afghanistan. He was elected to Congress in 2008, succeeding his father, also named Duncan, in the solidly Republican seat.