According to State elections director Chris Thomas, at least 31 people in Michigan voted twice during last year’s US presidential election.
Thomas said the names of those accused have been passed onto the Attorney General’s office and will face charges.
He added: “It’s not acceptable. There are processes in place to stop this. In these 31 cases, they didn’t work.”
The reports of fraud come a day after House Speaker Paul Ryan’s said he had “seen no evidence” that three to five million people voted illegally, as Mr Trump has claimed.
Trump confirmed his plans to fully examine his claims of electoral fraud last week.
He said: “I’m going to set up a commission headed by Vice-President Mike Pence and we’re going to look at it very, very carefully.”
Republicans in Washington ignored Trump’s remarks and said they will scrap to the Election Assistance Commission (EAC) which works with state and local officials to “ensure accessible, accurate and secure elections”.
Gregg Harper, the House Administration Committee Chairman, dismissed the organisation as “fluff” and as “perfect example of something that can be eliminated”.
Mr Thomas confirmed residents living in America’s mid-west voted twice; first with an absentee ballot and then in person.
Officials believe staff overseeing the Detroit ballots could not detect the double votes because they weren’t given an updated list of voters who had used an absentee ballot.
But the state Bureau of Elections said human error, not fraud or equipment failure, caused mismatches between the number of ballots.
Within Detroit alone, 14 of the 31 cases of fraud were found. But Mr Thomas claimed there was no “pervasive fraud” in their audit of the region.
Instead he felt that poll workers lacked sufficient training which in turn caused “widespread performance issues”.