IOWA CITY, Iowa (AP) — At least 12 Iowa residents wrongly had their ballots rejected in the 2012 presidential election because of inaccuracies in the state's list of ineligible felons, a review found Friday.

Secretary of State Matt Schultz announced that nine additional cases of improper disenfranchisement were found during a review launched after it was reported in January that three voters were disenfranchised because of bureaucratic mistakes.

The new cases include people who weren't felons but were wrongly included on the list and former offenders who had their voting rights restored and should have been removed.

The announcement is a potential embarrassment for Schultz, a Republican who is running for Congress and has made fighting voter fraud the focus of his tenure. His office funded a controversial $280,000 investigation that has led to felony charges against several people who are accused of illegally voting as felons.

Many of them say they were confused by policy changes on how and when former offenders have their voting rights restored, and believed they could vote. Last month, a jury took less than 40 minutes to acquit the first person to contest such a charge after concluding she had no criminal intent.

Friday's announcement shows that elections and court officials have struggled to track voter eligibility due to record-keeping errors.

Under Iowa's constitution, anyone convicted of an "infamous crime" loses the right to vote and hold office until restored by the governor. Everyone agrees that includes felons, but Iowa's top lawyers disagree on whether people convicted of aggravated misdemeanors are affected. The Iowa Supreme Court is weighing that question.

Ex-offenders long had to apply to the governor to receive voting rights back. Then-Democratic Gov. Tom Vilsack changed that policy, signing a 2005 executive order that restored voting rights for thousands who'd completed their sentences. Under state policy from 2005 to 2011, offenders automatically had their rights restored when they left state supervision. Republican Gov. Terry Branstad rescinded that policy in 2011, requiring ex-offenders to complete a lengthy application process for restoration, which only a few dozen have done.

Schultz, whose office is responsible for maintaining the list of 46,000 ineligible felons, told lawmakers in February that the data is filled with so many inaccuracies that it could take years to fix. Court officials send his office names to add after convictions, while the governor's office sends names of those restored to be removed.

Schultz said Friday that due to data entry mistakes, two felons weren't taken off the list after their rights were restored because the names associated with convictions didn't match their restoration names. He said six others had their rights restored by Vilsack's order but were never removed. One felon had his rights restored in 2010, but it wasn't entered into the database.

It wasn't clear why two non-felons were on the list. The third was charged with a felony in 2006 but never convicted.

All 12 were flagged as ineligible felons when they registered at polling places, but were allowed to cast provisional ballots that could be counted afterward if they proved eligibility. The ballots were rejected by precinct boards.

Schultz instructed county auditors Friday to work with local police to verify voters' felon status before rejecting provisional ballots in the future. He also formed a task force to "come up with a long-term solution to fix inaccuracies" in the list.

One voting rights group said other former offenders were probably disenfranchised because Iowa's process for identifying felons was "fundamentally broken."

"While the state has devoted extensive resources to finding instances of ineligible felons voting, it's neglected to correct its own database to ensure the removal of individuals who had their right to vote restored as far back as 2005," said Jon Sherman, attorney for the Fair Election Legal Network in Washington D.C. "Perhaps the Secretary should spend more time protecting this precious right."