JACKSONVILLE, Fla. – One day after U.S. Rep. Corrine Brown said her district is "under siege," neither she nor anyone else will talk about an apparent federal investigation of her office.

With Brown, D-Jacksonville, not taking calls and the U.S. Justice Department not acknowledging the subpoena that media reports said was served on Brown on Monday night while she was having dinner at a Northside Bono's Barbecue, political observers are left to speculate on what is under investigation.

Brown filed suit two weeks ago in federal court, challenging Florida's new court-ordered congressional districts that change the district she represents from a north-south orientation stretching from Duval County to Orlando to an east-west district that reaches from Jacksonville to past Tallahassee.

"It is not surprising that every time we go through the redistricting process some tangential investigation comes up," Brown said in a statement released Wednesday afternoon. "I want to assure my constituents that these unfounded and politically motivated actions will not distract me from my critical work of ensuring that the federal forces and rights of the 5th Congressional District are being protected."

A longtime consultant of the congresswoman said Wednesday she declined to talk to federal investigators who came to her door.

Von Alexander, a Democratic consultant and onetime employee of Brown's congressional office, told News4Jax that she directed the federal agents to her lawyer. She also said she had heard that Brown received a subpoena for records, but she doesn't know the nature of the investigation.

"We're trying to figure it out," Alexander said Wednesday.

News4Jax political analyst Jennifer Carroll, who unsuccessfully ran against Brown in 2000 and 2002, said that by law, Brown is required to file a letter with the speaker of the House of Representatives saying that she has been subpoenaed.

"That has not been done to this date and she was apparently served Monday," Carroll said.

The FBI had no comment and the local U.S. Attorney's Office referred questions about the investigation to the Justice Department, which responded with a statement:

"As a matter of policy, the Department of Justice generally neither confirms nor denies whether a matter is under investigation. That would include confirming or denying whether a subpoena has been issued in a particular matter."

The head of the Duval County Democratic Party, Neil Henrichsen, said he didn't know the specifics of the situation and would not comment.

The Florida Times-Union reported that the subpoena may be tied to what is known as Corrine's Quick-Picks, a list of candidates endorsed by Brown in a flyer that resembles a sample ballot. Concerns have been voiced over the years over whether people had to pay to get on the list.

While federal investigators are not talking about the case, a News4Jax source said it has nothing to do with redistricting. Another credible source said the subpoena could be about use of campaign funds, but no one is going on the record about the nature of the investigation.

"I am not surprised that it is not out there yet, because if Congresswoman Brown has the control as to feeding the public, as to what this information is, of course you want to delay it until you can get your hands around it," Carroll said.