Ted G, Loza, Graham's former chief of staff, asked for or received more than $30,000 in cash, trips, limousine rides and meals in exchange for pushing laws favorable to the taxi cab industry, prosecutors said.
Loza was arrested in September 2009 and initially charged with two counts of bribery on allegations he accepted $1,500 in payments from Abdulaziz Kamus, an advocate for Ethiopian cab drivers who was trying to secure advantages for that community in the city's taxicab market.
In a superseding indictment filed this month, prosecutors added a count of conspiracy to commit bribery, an additional count of bribery, a count of extortion and a count of making false statements.
During today's hearing, Judge Paul Friedman asked whether a larger jury pool will be needed because of extensive news coverage of the case.
The trial is set for October. Prosecutors said it could last a month.
"We look forward to our day in court," Pleasant Brodnax III, Loza's attorney, told the Post.
Councilman Graham has repeatedly denied wrongdoing and has said he's fully cooperating with authorities.
Law enforcement officials told the Washington Post in September 2009 that Graham was not a target of their investigation.