State elections officials are seeking a criminal investigation into irregularities in the Harford County voter rolls, which they say have been artificially inflated.
The probe comes weeks after Harford officials reported the county had just enough active voters to qualify for additional early-voting centers in 2012.
State elections administrator Linda H. Lamone said a staff member in her office discovered names on the county's list of active voters that should have been classified as inactive, a designation that generally indicates people who have moved out of the state.
Lamone would not say how many records were affected, citing the continuing investigation.
The county board reported 151,146 active voters to the state by the Aug. 1 deadline — enough to qualify for three early-voting centers in next year's presidential election.
Lamone said Thursday that she believes the correct number is slightly less than the 150,000-voter cutoff. She said the county would have only one early-voting center next year.
Harford County elections board president Molly Neal said the board is conducting its own investigation in order to "restore faith" in the voter list. She said the is cooperating with state prosecutors.
Lamone said her auditor told her about the problem earlier this summer. She forwarded her office's report to the state prosecutor a few weeks ago.
"We routinely audit the system for accuracy," Lamone said. "When the auditors here discover any signs of mistakes, they investigate them further. … In this case, I decided to refer it to the proper authorities."
The office of the state prosecutor does not confirm or deny investigations.
Neal said she felt "extreme concern" about the situation when she learned of it two weeks ago. She said the board is cooperating with state prosecutors, and she has placed two staff members on administrative leave.
Neal said the addition of the inactive voters to the list of active voters did not benefit one political party over another. Republicans in Harford enjoy a slight edge over Democrats in voter registration.
Maryland elections officials move voters to an inactive list after the post office returns two letters from the board with no forwarding address. If a voter on the inactive list casts a ballot or signs a petition, he or she is automatically put back on the active rolls.
Last year was the first time voters were allowed to cast their ballots before Election Day at early-voting centers. More than 200,000 people statewide, or 6.4 percent of registered voters, participated.
Neal said turnout at Harford's early-voting center last year was "excellent" but manageable.
She said that she believes the county has enough population to support three centers, but the local board did not authorize any particular outreach effort to push past the 150,000 cutoff.
Aegis reporter Bryna Zumer contributed to this article.