WASHINGTON — The investigation into alleged election fraud involving absentee ballots in North Carolina is now focusing on unreturned absentee ballots, according to a source familiar with the investigation.

The N.C. State Board of Elections has been investigating alleged illegal activity involving absentee ballots in at least two counties in the 9th Congressional District race between Republican Mark Harris and Democrat Dan McCready.

The board announced Friday that it will conduct a public evidentiary hearing into the alleged irregularities on Jan. 11, pushing back any resolution of the race until after the new congressional term begins. The board had said it intended to have the hearing before Dec. 21.

The investigation has centered on the activity of Bladen County operative McCrae Dowless, who has worked for Republican and Democratic campaigns. He was paid by the Red Dome Group, which was contracted by Harris, for "get out the vote" efforts in the 9th District. Harris is the unofficial winner for he election by a narrow 905 votes, and he won 60 percent of the absentee ballot vote in Bladen County despite only 19 percent of absentee ballot voters identifying as Republican.

The focus on unreturned ballots suggests investigators may be more concerned that Dowless and his associates may have discarded ballots they collected, rather than they may have altered them. It is illegal for unauthorized people to collect absentee ballots in North Carolina and it is also illegal to alter a voter's ballot.

A sworn affidavit obtained by NBC News this week was signed by Kenneth Simmons, who said that he saw Dowless with a large number of absentee ballots. Simmons said Dowless told him that he had 800 ballots on his person and that he wouldn't turn them in until the last day so the other side doesn't know how many votes they need.

The State Board of Election released a document last week that shows that Bladen County ran the accumulation of its vote total of early voting the Saturday before Election Day, which is also illegal.

The board, according to the source, said that it has information that "indicates that unauthorized persons could have illegally requested and received actual absentee ballots in voters’ names by submitting forms containing the voters’ personal identification information."

In order to request an absentee ballot, a voter must submit personal information, including a drivers' license number or a social security number.

Dowless turned in 590 absentee ballot applications, according to documents released by the Board of Elections.

The North Carolina legislature also passed legislation that would call for a new primary election if the board of elections calls for a new general election. But Gov. Roy Cooper has not yet signed the bill into law.