The Yavapai County Attorney's Office will investigate allegations that Arizona Attorney General Tom Horne and one of his aides violated campaign-finance laws during Horne's 2010 election campaign.
The Arizona Republic reported Wednesday that Yavapai County Attorney Sheila Polk will oversee the case.
Maricopa County Attorney Bill Montgomery accused Horne and Kathleen Winn of collaborating to quickly raise more than $500,000 to fund negative ads targeting Horne's Democratic opponent during the 2010 election.
By law, candidates are not allowed to coordinate certain activities with independent-expenditure committees.
Horne defeated ex-prosecutor and bank regulator Felicia Rotellini by about 63,000 votes out of a total of 1.6 million ballots cast in the 2010 general election.
Horne and Winn say they did nothing wrong and that authorities have misinterpreted evidence.