Tunheim was born in
Thief River Falls, Minnesota, in 1953. He attended
Concordia College in
Moorhead, Minnesota, and received a
Bachelor of Arts degree in 1975. He then attended the
University of Minnesota Law School, receiving his
Juris Doctor in 1980. From 1980 to 1981, Tunheim was a
law clerk for Judge
Earl R. Larson of the United States District Court for the District of Minnesota. From 1981 to 1984, he was in private practice in
Saint Paul, Minnesota. He then joined the Office of the State Attorney General of Minnesota, serving as an assistant state attorney general and the manager of the Public Affairs Litigation Division from 1984 to 1985, as Minnesota state solicitor general from 1985 to 1986, and as chief deputy state attorney general from 1986 to 1995. He was an adjunct professor in the
University of Minnesota Law School in 1994. Tunheim also chaired the
Assassination Records Review Board, which oversaw the collection of records relating to the
assassination of John F. Kennedy, from 1994 to 1995. Tunheim was interviewed for the 2021 documentary
JFK Revisited: Through the Looking Glass. In 2025 he testified at the second hearing of the
House Oversight Committee's "Task Force on the Declassification of Federal Secrets". ==Federal judicial service==