Jonathan Marks, commissioner for Pennsylvania's Bureau of Commissions, Elections and Legislation, told a state legislative committee that an agency analysis found 544 improper ballots cast between 2000 through 2017.

The election commission says those ballots were cast by noncitizen immigrants who claim they had mistakenly registered to vote, reports the Associated Press. In response to questions from Republican lawmakers, the commission said it was investigating if other noncitizen immigrants remain registered to vote.

The hearing comes two weeks after former Pennsylvania Secretary of State Pedro Cortes abruptly resigned amid disclosures that legal resident noncitizens were able to register to vote while applying for or renewing drivers licenses.