Smith did not return a request for comment on Wednesday.
Smith resigned his state Senate seat on Aug. 25 following his guilty plea.
During his 2004 campaign, Smith knowingly allowed an independent group to produce two mailers denouncing his opponent, according to a press release on his web site.
Federal law prohibits coordination between a campaign and any independent entity spending money on the election. Smith denied knowledge of the group's activities and filed a false affidavit during the Federal Election Commission's 2004 investigation, according to the press release.
Smith enlisted the help friends Nick Adams and former U.S. Rep. Steve Brown, D-Mo., to cover up his actions, according to the St. Louis Post Dispatch.
The case was reopened in 2009 after the FEC received new information, and officials approached Brown and Adams to help with the investigation.
If Smith had cooperated with FEC officials in 2004, he would likely have been charged with a civil infraction and received only a fine, but Smith's deception increased the penalties he faced, according to the Post-Dispatch.
Brown pled guilty to one count of obstructing justice and received a $40,000 fine and two years of probation. Adams received two years of probation and a fine of $5,000 for conspiracy to obstruct justice.
At Dartmouth, Smith served as a visiting government professor from Winter 2005 to Summer 2006. He taught courses on campaigns and elections, Congress and the American political system, and contemporary American politics.
Four Dartmouth students spent a leave term volunteering for Smith's victorious 2006 campaign for the Missouri state Senate.
"When we were running the state Senate campaign, we were running it squeaky clean," Henry Whitehead '07, who volunteered for the campaign, said in an interview with The Dartmouth. "He was all about the issues and not dirty campaigning."
Several of Smith's friends, including Missouri Attorney General Chris Coster, sent letters to the court commenting on his personal characteristics and accomplishments, according to the Post-Dispatch. Smith established the Missouri Teaching Fellows Program, which aids poorer school districts and rewards academic progress.
"Your service has been significant, perhaps extraordinary," U.S. District Judge Carol Jackson told Smith in his trial. "You touched a lot of people's lives. Perhaps people are wondering, Who is the real Jeff Smith?'"
Smith's 2004 campaign was the subject of a recent documentary by Frank Popper, "Can Mr. Smith Get to Washington Anymore?"
Whitehead, who took the course "Race and Ethnicity in American Politics" with Smith during his sophomore year, said he is disappointed by Smith's actions, but happy that Smith chose to plead guilty.
"I hope it doesn't really set back the progressive movement in Missouri the way that it has the potential to," he said.
St. Louis Democrat Joe Keaveny was sworn in on Wednesday in to fill Smith's now-vacant seat, the Post-Dispatch reported.
