As D.C. Mayor Vincent Gray attended the Democratic National Convention on Tuesday, a federal prosecutor said that the investigation into Gray's campaign that has netted guilty pleas from three operatives remains active.

"The investigation continues," Assistant U.S. Attorney Ellen Chubin Epstein said at a status hearing for Thomas Gore, assistant treasurer of the 2010 campaign and a longtime friend of the mayor's.

Gore, who acted as the campaign's day-to-day treasurer, pleaded guilty in May to a felony obstruction of justice charge, as well as three campaign finance violations.

Under the terms of his plea agreement, Gore faces up to 18 months in prison.

A sentencing date has not been set, though, because Epstein said Gore is still assisting authorities in their probe. U.S. District Court Judge Colleen Kollar-Kotelly, who is overseeing the cases involving the three Gray campaign operatives, set another status hearing for Dec. 12.

Prosecutors opened an investigation into the Gray campaign after Sulaimon Brown, a minor mayoral candidate, went public in March 2011 with allegations that Gray aides had paid him and promised him a job in exchange for his agreement to remain in the race. According to Brown, the Gray campaign wanted him to remain a candidate so he could criticize Gray's chief rival, then-incumbent Mayor Adrian Fenty, during primary debates.

In a court filing, Gore acknowledged he played a starring role in the scheme and the cover-up as authorities closed in on him and others, shredding a notebook with a record of payments to Brown.

Gore also acknowledged he purchased several money orders that another person -- Gray campaign consultant Howard Brooks -- used to pass funds to Brown and his campaign.

Gore declined to answer questions after his appearance and even broke into a light jog after a WTTG-TV photographer approached. Fred Cooke, who is representing Gore, said his client recognized his proceedings would not conclude quickly.

"We're in this until it's over," Cooke told reporters. "Until it's over, you can't do anything except live with it. You don't have a lot of choices."

Gore was the first Gray campaign official to plead guilty to charges stemming from the sweeping federal investigation.

Brooks pleaded guilty not long after Gore entered his plea. He will be sentenced in October.

The Brown matter is just one occurrence within the Gray campaign that has attracted the scrutiny of federal authorities. In July, Jeanne Clarke Harris, a onetime communications consultant for Gray, pleaded guilty to her role in designing a $653,800 shadow campaign.

People familiar with the case have said Jeffrey Thompson, a prominent city contractor and campaign donor, is believed to have financed that effort, but he has not been charged. His attorney, Brendan Sullivan, has not responded to repeated requests for comment.

Gray has denied any wrongdoing.

ablinder@washingtonexaminer.com