One of U.S. Rep. William Jefferson's sisters pleaded guilty Wednesday to concealing a crime for her role in alleged scheme to defraud the federal government.

Brenda Jefferson, 52, pleaded guilty to misprision of a felony. Prosecutors have charged three other Jefferson family members with pocketing more than $600,000 in state and federal grant money intended for charitable and educational projects.

New Orleans tax assessor Betty Jefferson, her brother, Mose Jefferson, and her daughter, Angela Coleman, are scheduled to appear in court Friday on charges that include federal program fraud, identity theft and conspiracy to commit money laundering.

Brenda Jefferson, also known as Brenda Foster, admitted to helping conceal the alleged scheme. Her attorney, Robert Jenkins, said she is cooperating with federal investigators.

"She went in and accepted her guilt and responsibility," Jenkins said. "It was a very difficult decision based on the relationship she has with her family members."

Rep. Jefferson was indicted last year on unrelated bribery charges and is awaiting trial. He has denied any wrongdoing. On Tuesday, the nine-term Louisiana Democrat announced plans to run for re-election.

Brenda Jefferson is the youngest of 10 siblings. The Covington woman faces up to three years in prison and a fine of $250,000. Her sentencing is set for Sept. 24.

Brenda Jefferson worked as a secretary for nonprofit companies that Betty and Mose Jefferson used to get grants to help pregnant teens, at-risk youths and others, prosecutors said.

Betty and Mose Jefferson are accused of deposited some of the grant money into personal checking accounts and using it for personal expenses. Brenda Jefferson was paid roughly $90,000 for her work, according to prosecutors.

"The government's evidence thus would show that while (Brenda Jefferson) knew of the fraudulent scheme and even received proceeds from it, she participated primarily at the direction and behest (of her relatives)," said a court document that prosecutors and Brenda Jefferson signed.

Ike Spears, a lawyer for Mose Jefferson, didn't immediately return a call for comment Wednesday.

Mose Jefferson, 66, pleaded not guilty in April to separate charges that he paid bribes to a former New Orleans school board president. Betty Jefferson, 70, also was charged this month with four counts of tax evasion.

Court documents did not list an attorney for Betty Jefferson or her daughter.