Indiana State Police said on Thursday that they have expanded an investigation of possible voter registration fraud to 57 of the state’s 92 counties.

The investigation expanded from nine counties state police said they were investigating on Tuesday. Capt. Dave Bursten, state police spokesman, provided no details on the reason for the expansion.

The announcement came about an hour after Patriot Majority USA, a group that runs the Indiana Voter Registration Project that is under investigation in the nine counties named Tuesday, said it asked the U.S. Department of Justice’s Civil Rights Division to look into whether the investigation is an attempt to suppress black votes.

Bursten denied any attempt to suppress votes, saying the investigation has followed proper procedures. It has looked into whether fraudulent names or addresses were used in registering voters.