LANSING (WWJ/AP) – Michigan Secretary of State Ruth Johnson says she’s asked the state Attorney General’s office to investigate 10 people who aren’t U.S. citizens but have voted in past Michigan elections.

In a letter to Attorney General Bill Schuette, Johnson said they were referring the cases “for  investigation, and if appropriate, prosecution.”

READ MORE: New York City Announces First-In-The-Nation Vaccine Mandate For Private Companies

“The law is clear – you must be a U.S. citizen to register to vote and to  vote on Election Day,” Johnson said in a statement. “We have races that are decided on a  handful of votes, and ballots cast by ineligible voters cancel out those by legitimate voters.”

The Secretary of State’s office says the people are from Kent, Macomb, Oakland, Roscommon and Wayne counties. Names of those involved haven’t been released, but Johnson’s office says they voted in presidential and gubernatorial elections in the past decade.

Schuette spokeswoman Joy Yearout says they received the letter from Johnson and the referrals are under review.

READ MORE: Sharon Gless On Book 'Apparently There Were Complaints: Cagney & Lacey 'Changed The History Of Television For Women'

In October, Johnson’s office sent letters to more than 600 registered Michigan voters, verified as non-U.S. citizens by federal records, asking them to contact state election officials to be removed from Michigan’s voter rolls. After the letter was sent out, dozens of people responded and requested to be immediately removed from Michigan’s voter rolls. The 10 individuals  referred to the Attorney General’s office did receive the letter.

Election officials acknowledge that some non-citizens on the voter rolls may have registered inadvertently because for decades, Secretary of State branch clerks were required by the federal government to ask every customer, regardless of citizenship, if they wanted to register to vote. Procedures have since  changed.

Non-citizens who register and vote can face criminal charges and hurt their ability to become a U.S. citizen.

Recently, a non-citizen who resided in Macomb County was charged with voter fraud for registering to vote. In Berrien County,  another non-citizen was sentenced to 10 days in jail for voter fraud for voting  in the 2008 election. In Kalamazoo County, a non-citizen who believed he was legally able to vote had his attempt at becoming a U.S. citizen jeopardized in 2011 after federal officials determined he had voted numerous times.

MORE NEWS: How Unusual To Charge Parents In School Shooting?

TM and © Copyright 2013 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2013 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.