At least 12 mailed ballots were stolen in a rural Colorado county and then sent in with fraudulent votes, three of which slipped past county election officials and were counted in next month’s general election, state officials said Thursday.

A fourth ballot was almost counted, but the voter — who had not received their ballot — received an electronic notification that their ballot had been accepted by the elections office and contacted the clerk, Secretary of State Jena Griswold said during a news conference in Denver.

The fraudulent votes were discovered during the voter signature verification process, enabling Mesa County election officials to stop eight of the ballots before they were counted, Griswold said. The county had counted over 27,000 ballots by Wednesday.

The three fraudulent votes that were counted cannot be removed from the tally. Because ballots themselves are not signed, once they are removed from the signature envelope, there is no way to identify them.

It appeared some of the ballots were signed by the same person, she said, but Griswold declined to comment on any possible motive or the investigation being done by Mesa County and the U.S. Postal Inspection Service. The district attorney’s office did not return a phone call seeking comment.

The fraudulent voting occurred in the same county where former elections clerk Tina Peters was recently sentenced to prison for a data breach scheme spawned from false claims about voter machine fraud in the 2020 presidential race.

Griswold, a Democrat, called the incident unfortunate but sought to reassure people Colorado’s elections are safe and secure.

“This attempt at fraud was found and investigated quickly because of all the trailblazing processes and tools Colorado has in place like signature verification, ballot tracking, and the curing process,” said Griswold, citing a measure in which voters are notified if the signature on their ballot envelope doesn’t match the signature on their voter registration card.

The voters who did not receive their mailed ballots will be given a new ballot to vote, Griswold said.

Peters’ replacement, Mesa County Clerk and Recorder Bobbi Gross, also a Republican, issued a statement indicating she was not happy Griswold had called a press conference, saying she believed that “prematurely releasing details could compromise our ability to hold those responsible accountable.”

“The people of Mesa County deserve transparency and accountability, but it must be done in a manner that protects the integrity of the investigation,” Gross said.

Amy Beth Hanson, The Associated Press