"I find it awfully suspicious, that if there is an investigation that the [Associated Press] was tipped off before we were tipped off or our lawyer or any other officials," O'Donnell said during an interview on American Morning. "And as we've looked into it, this is simply the same CREW complaint that is obviously politically motivated that's been circulating for the past couple of months."
Justice Department prosecutors and FBI agents have started the investigation, a source with knowledge of the probe confirmed to CNN. The source could not speak on the record because of the investigation is deemed sensitive. The source would not provide any further details and the FBI and Justice Department had no comment. News of the investigation was first reported by the Associated Press.
When O'Donnell ran in the Republican primary and in the general election campaign, she faced repeated questions about her finances, including the use of her home that doubled for a time as her campaign headquarters. She acknowledged using some campaign funds to help pay the rent but is adamant she did not nothing wrong.
"We rent a townhouse that we use for the campaign headquarters," O'Donnell told CNN Thursday. "And because of things like eggs being thrown at my home and my home being broken into and vandalized, I use that townhome as my legal residency, and I pay the campaign rent in order to do that. I give the campaign money to have that as my legal residency. Not the other way around. So these things are being taken out of context."
The former Delaware Senate candidate also attributed the rumors of impropriety to a disgruntled former campaign volunteer, David Keegan, who submitted an affidavit to watchdog group Citizens for Responsibility and Ethics (CREW) alleging misuse of campaign funds in a previous O'Donnell Senate bid.
"Dave Keegan was a volunteer in 2008 so how did he know about anything in 2009?" O'Donnell responded. "We let him go because he gave so many people on the campaign the creeps. Since then, he's become obsessed for whatever reason with putting the charges out there."
CREW subsequently filed complaints with the Federal Elections Commission and the U.S. Attorney's Office in Delaware regarding O'Donnell's finances, asking for investigations of her alleged use of campaign funds for personal expenses.
Justice Department spokeswoman Laura Sweeney acknowledged to CNN that the U.S. Attorney's office in Delaware had agreed to review the initial complaint filed by CREW. However, Sweeney declined to say whether federal prosecutors and FBI agents had gone beyond the initial review.
In a statement issued Wednesday, O'Donnell also suggested the investigation was the work of Vice President Joe Biden, the former longtime senator from Delaware.
"Given that the King of the Delaware Political Establishment just so happens to be the Vice President of the most liberal Presidential administration in U.S. history, it is no surprise that misuse and abuse of the FBI would not be off the table," she said.
A spokesman for Biden's office had no comment on O'Donnell's allegation.
O'Donnell, who shocked Republicans with her surprise primary victory over Rep. Mike Castle last fall, also told CNN the investigation is evidence of the political establishment's ongoing vendetta against her.
"Keep in mind, that we upset the Delaware political establishment," she said. "And we beat their so-called untouchable incumbent. There's a vendetta to stop this movement in its tracks because if the citizen politicians continue to rise up and put the career politicians on notice, we are going to continue to put the political establishment on notice."