In 2006, Marty was appointed and unanimously confirmed by the U.S. Senate as U.S. Attorney for South Dakota. He was the recipient of the Prosecutor of the Year award in 2008 for outstanding prosecutorial service.

From 2009 to 2019, Marty served as South Dakota’s Attorney General. In 2015, he served as Chairman of the National Association of Attorneys General and also as a past Chairman of the Western Attorneys General. In 2016, Marty received the National Attorney General of the Year award from his fellow Attorneys General.

After serving 10 years as South Dakota Attorney General, Marty returned to the Rapid City law firm of Gunderson, Palmer, Nelson and Ashmore as a senior partner, opening a Pierre branch office. He also served as State’s Attorney for both Jones and Haakon counties, and as a Special Prosecutor for the Sisseton Wahpeton Oyate. Marty received the State’s Attorney’s Distinguished Service Award in 2019.

In 2022, Marty was elected for a fourth term as the South Dakota Attorney General. For the 2023–2024 year, he served as Chairman of the Attorney General Alliance. In 2024, he was elected Vice Chairman of the National Attorneys General Association.

Marty has two children: Michael, who is studying Mechanical Engineering at South Dakota State University, and Isabella, a biology major also at SDSU. Marty enjoys spending family time at his farm in Vale, South Dakota, and his ranch near Pierre, South Dakota.