ALEXANDRIA, Va. – A congressman under investigation for bribery was caught on videotape accepting $100,000 in $100 bills from an FBI informant whose conversations with the lawmaker also were recorded, according to a court document released yesterday. Agents later found the cash hidden in his freezer.

At one audiotaped meeting, Rep. William Jefferson, a Democrat of Louisiana, chuckles about writing in code to keep secret what the government contends was his corrupt role in getting his children a cut of a communications company’s deal for work in Africa.

As Mr. Jefferson and the informant passed notes about what percentage the lawmaker’s family might receive, the congressman “began laughing and said, ‘All these damn notes we’re writing to each other as if we’re talking, as if the FBI is watching,'” according to the affidavit.

Mr. Jefferson, who represents New Orleans, has not been charged and denies any wrongdoing.

As for the $100,000, the government says Mr. Jefferson got the money in a leather briefcase last July 30 at the Ritz-Carlton hotel in Arlington. The plan was for the lawmaker to use the cash to bribe a high-ranking Nigerian official – the name is blacked out in the court document – to ensure the success of a business deal in that country, the affidavit said.

All but $10,000 was recovered on August 3 when the FBI searched Mr. Jef ferson’s home in Washington.The money was stuffed in his freezer, wrapped in $10,000 packs and concealed in food containers and aluminum foil.

Two of Mr. Jefferson’s associates have pleaded guilty to bribery-related charges in federal court in Alexandria. One, businessman Vernon Jackson of Louisville, Ky., admitted paying more than $400,000 in bribes to the lawmaker in exchange for his help securing business deals for Jackson’s telecommunications company in Nigeria and other African countries.

The new details about the case emerged after federal agents searched Mr. Jefferson’s congressional office on Capitol Hill on Saturday night and yesterday. The nearly 100-page affidavit for a search warrant, made public yesterday with large portions blacked out, spells out much of the evidence so far.

The document includes excerpts of conversations between Mr. Jefferson and an unidentified business executive from northern Virginia. She agreed to wear a wire after she approached the FBI with complaints that Mr. Jefferson and an associate had ripped her off in a business deal.

Mr. Jefferson’s lawyer, Robert Trout, contended that the prosecutors’ disclosure was “part of a public relations agenda and an attempt to embarrass Congressman Jefferson. The affidavit itself is just one side of the story which has not been tested in court,” Mr. Trout said in a statement.

The affidavit says Mr. Jefferson is caught on videotape at the Ritz-Carlton as he takes a reddish-brown briefcase from the trunk of the informant’s car, slips it into a bag, puts the bag into his 1990 Lincoln Town Car, and drives away.

The $100 bills in the suitcase had the same serial numbers as those found in Mr. Jefferson’s freezer.

While the name of the intended recipient of the $100,000 is blacked out, other details in the affidavit indicate he is Abubakar Atiku, Nigeria’s vice president. He owns a home in Potomac, Md., that authorities have searched as part of the Jefferson investigation.

Mr. Jefferson assured the FBI informant in their coded conversations that he paid the money to the Nigerian official, even though the money was still in Mr. Jefferson’s possession when agents searched his home August 3.

On August 1, two days after Mr. Jefferson picked up the $100,000, the informant called Mr. Jefferson to ask about the status of “the package.”

Mr. Jefferson responded: “I gave him the African art that you gave me and he was very pleased.”

When Mr. Jefferson and the informant had dinner at a Washington restaurant on May 12, 2005, the FBI was listening, too. Mr. Jefferson indicates he will need an increased stake in the profits of one deal, the affidavit said. Instead of the 7% stake originally agreed upon, he writes “18-20” on a piece of paper and passes it to the informant.

That is when negotiations move ahead and notes go back and forth, ending with Mr. Jefferson’s laughter about the FBI watching it all.