The Justice Department refused to say what agents were looking for during the searches of U.S. Rep. William Jefferson's homes and vehicle.

"As it is a criminal investigation we will not be able to comment any further," said Bryan Sierra, a Justice Department spokesman.

Jefferson, 58, an eight-term Democrat from New Orleans, said in a statement that he did "not know the extent or precise nature of this investigation" but said he was cooperating fully.

Jefferson's office said the congressman was in New Orleans and was not available for further comment.

His name surfaced earlier in a case involving his brother-in-law, a former state judge convicted in June of mail fraud in a wide-ranging probe of bail bond corruption in suburban New Orleans.

According to federal court documents, the lawmaker asked Alan Green in a recorded conversation to raise money for his daughter's successful 2003 campaign for the Legislature. The records show that Green agreed to help.

The Louisiana Code of Judicial Conduct bars judges from asking for campaign donations on behalf of political candidates.

Jefferson has said he recalled the conversation with Green, but the request for help was familial _ and not political _ in nature.

"To my knowledge, nothing resulted from the conversation _ the campaign did not receive any money from Judge Green or anyone who may have been prompted by him to contribute," Jefferson said.

State Rep. Jalila Jefferson-Bullock, a Democrat, has said that she had no knowledge of the matter and did not receive contributions from Green, directly or indirectly. She said late Wednesday that she knew nothing about the raid.

Jefferson was elected to Congress in 1990 as the first black House member in the state since Reconstruction. He serves on the influential House Ways and Means Committee.

In June, the FBI searched the yacht and California home of U.S. Rep. Randy "Duke" Cunningham, whose business dealings are under investigation by a federal grand jury in San Diego.

The inquiry began after reports that Cunningham sold his house to a defense contractor who quickly put it back on the market and later sold it at a $700,000 loss.

Cunningham, a Republican, has denied any wrongdoing but has announced he will not seek re-election to a ninth term next year.