Updated

Prosecutors brought a campaign finance charge against the former chairman of the District of Columbia Council on Thursday, one day after he resigned from his seat and agreed to plead guilty to federal bank fraud.

The misdemeanor violation adds to Kwame R. Brown's legal woes and comes a day before his expected guilty plea in the federal case.

Brown, among the most powerful figures in local politics, was charged in federal court Wednesday with falsifying his income by tens of thousands of dollars on loan applications. He submitted his resignation later in the day and apologized for his actions.

"I have made some very serious mistakes in judgment for which I will take full responsibility," Brown, 41, said in the letter.

The remaining councilmembers are scheduled to meet next week to select a new interim chairman from the four at-large members.

The three-page misdemeanor charge, filed in D.C. Superior Court, accuses Brown of allowing a relative to open a second bank account, ostensibly to cover "get-out-the-vote" efforts, during his 2008 reelection campaign. That relative was permitted to make withdrawals from that second account, or "side account," on behalf of the campaign committee, prosecutors say.

The relative used campaign funds in September 2009, after the election, on a cash expenditure "in excess of $50 to a person in connection with a single purchase and transaction," according to court documents.

The relative is referred to in court documents only as "Person 1," but an Office of Campaign Finance complaint from last year that includes similar allegations says the second bank account — or "side account — contained $60,000 and listed Brown's brother, Che Brown, as a signatory.

The office concluded that Brown had failed to timely report more than $270,000 in campaign contributions and expenditures and that a consulting firm operated by Che Brown received about $239,000 in funds. The office also found that Brown's campaign had failed to update its "statement of organization" to reflect or include Che Brown as an officer with signatory authority.

The D.C. board of elections and ethics referred the campaign irregularities to the U.S. Attorney's office last summer.

A lawyer for Kwame Brown declined comment Thursday, and a lawyer for Che Brown, who has not been accused of wrongdoing, did not return messages seeking comment.

The criminal charges against Brown further unsettle local politics in the nation's capital. Another councilmember, Harry Thomas Jr., pleaded guilty in January to embezzling more than $350,000 in government funds earmarked for youth sports and arts programs. He has been replaced on the council.

And two former campaign aides to Mayor Vincent Gray pleaded guilty to federal charges last month stemming from improper payments made so a minor candidate in the 2010 race would continue denigrating the then-incumbent Adrian Fenty, who was seeking re-election. That investigation is continuing, and Gray has denied any wrongdoing or knowledge of the payments.