One woman was charged Friday with forgery after a statewide probe into alleged voting fraud, but the South Dakota attorney general said other allegations that some people were paid to vote are false.

Attorney General Mark Barnett, a Republican, conducted the investigation after GOP supporters of Rep. John Thune collected about 50 affidavits from poll watchers and others claiming voting irregularities, largely on American Indian reservations.

Thune lost last month's Senate race by 524 votes to Democratic incumbent Tim Johnson. Thune declined to seek a recount, and has said he believes that although there were irregularities, resolving them would not change the outcome.

Becky Red Earth-Villeda, a former independent contractor with the state Democratic Party, was charged with 19 counts of forgery for allegedly falsifying requests for absentee ballots on some reservations. Each forgery charge carries a maximum prison term of five years.

Investigators connected Red Earth-Villeda to 1,765 absentee ballot applications in 25 counties, said James Vlahakis, a state Division of Criminal Investigation supervisor. Of 381 people interviewed, 277 said their signatures were forged, he said.

FBI agents, who also were involved in the investigation, discovered 15 more voters who said their names were forged on election documents, Vlahakis said.

Barnett said that although Red Earth-Villeda was charged with forging absentee ballot applications, she was not linked to improper voting.