The former U.S. senator faces a possible criminal indictment if the grand jury decides enough evidence exists that he violated campaign finance laws.
When Edwards met last week with the aging donor who contributed money that was allegedly used to cover up Edwards' affair with a campaign staffer, those familiar with the case questioned the timing.
Former Edwards aide Andrew Young wrote in his tell-all book, "The Politician," that heiress Rachel "Bunny" Mellon gave Edwards a total of $700,000 as a gift. The so-called "Bunny money" helped fund the cover-up the candidate's affair with video producer Rielle Hunter, who was pregnant with the his child during the 2008 presidential campaign.
Federal agents have interviewed Mellon at least twice during the course of the investigation, sources told WRAL News. Her attorney acknowledged that Edwards visited Mellon's Virginia estate last week but told the Associated Press that they did not discuss the case.
Young told WRAL News in a 2010 interview that Edwards' campaign finance chairman, wealthy Texas lawyer Fred Baron, also financed flights and paid rent on a California home for Hunter and Young's family during the period when Young pretended to be the father of Hunter's baby.
Baron died from cancer in 2008, but his widow appeared before the federal grand jury in Raleigh in January.
The case has been under review by the Department of Justice in Washington, D.C., in recent months, and officials recently signed off on prosecuting Edwards.
Sources have told WRAL News that Edwards is considering a plea deal to conclude the investigation.
Political observers have said the money from Mellon was a campaign contribution and should have been noted in Edwards' campaign finance reports.
"I really think it's an important case," said David McLennan, a political science professor at Peace College. "In my view, the money was no gift. It can't be classified that way because it was to further John Edwards' run for president."
If prosecutors are successful in going after Edwards for not reporting the money, it could have a legal impact on other political candidates and the money that flows around them.
Greg Craig, a Washington, D.C., attorney representing Edwards, issued a statement last week questioning the government's case.
"John Edwards has done wrong in his life – and he knows it better than anyone – but he did not break the law," said Craig, a former White House counsel. "The government's theory is wrong on the facts and wrong on the law."