The former chief of staff to one-time D.C. council member Harry Thomas Jr. pleaded guilty Friday to falsifying tax documents in connection with payments for a 2009 political ball.

Ayawna Webster, who was also president of the D.C. Young Democrats, is the sixth person to be charged in the Thomas investigation. The former Ward 5 council member, who resigned last year, is serving a 38-month jail sentence for his theft of more than $350,000 from the D.C. Children and Youth Investment Trust.

In charging documents filed Thursday, Webster is accused of falsifying tax documents and failing to file a tax return on behalf of the D.C. Young Democrats to reflect $104,500 in grant funds the organization used to pay for the ball at the John A. Wilson building.

Webster “assisted in concealing from the Internal Revenue Service” that the Young Democrats were the “true beneficiary of the grant of public funds.”

The investigation into the D.C. Children and Youth Investment Trust found that Thomas requested and received more than $100,000 from the former head of the non-profit when funding for the event fell short.

The former head of the non-profit trust, Millicent West, pleaded guilty in February to tax-related charges and is awaiting sentencing.

According to court documents, West worked with Thomas and Webster to send trust money intended to pay for youth programs to help cover the cost of the party. West suggested that Thomas find another organization to handle the payment because of concerns about cutting a check for a political group.

Thomas then instructed his staff to arrange for the trust to grant money to another nonprofit, Youth Tech, which in turn paid the Young Democrats, according to court documents. Youth Tech’s executive director, Danita Doleman, is among those who have pleaded guilty in the scheme.

Webster faces a maximum of three years in prison and a $250,000 fine. She is scheduled to be sentenced Nov. 1. Both she and her attorney declined to comment after the hearing Friday.