KANSAS CITY, KAN. — A federal prosecutor said on Monday that her office was asking defense attorneys in a major Douglas County and Johnson County drug trafficking case to disclose information about their fees as investigators seek to identity proceeds from alleged drug sales.

Assistant U.S. Attorney Terra Morehead said in court on Monday that the Internal Revenue Service was investigating the source of funds for a number of defendants in the case.

“We’ve been seizing considerable assets,” she said.

The case involves the indictment of 35 defendants, including 11 Lawrence residents, on drug conspiracy and other federal charges. Prosecutors accuse members of the group of working to distribute a mixture containing cocaine and more than 1,000 kilograms of marijuana from 2005 to June of this year.

Prosecutors are seeking a $16.9 million judgment, alleging the defendants obtained that amount over the seven years of drug distribution, and U.S. Attorney Barry Grissom’s office has claimed two Lawrence residents, Los Rovell Dahda, 30, and Chad Eugene Bauman, 33, made millions as leaders of the effort.

Morehead told a judge in court on Monday in front of almost all 35 defendants that investigators believed “a number of defendants” had hidden assets and income “even since they’ve been in custody.” Federal and state officers rounded up most defendants in June in Lawrence and elsewhere. Morehead said the government would make available much more evidence than is required under federal rules to defense attorneys who complied with the fee disclosure request.

All defendants in the case pleaded not guilty to charges in the indictment on Monday in front of U.S. Magistrate Judge James P. O’Hara. Most of the defendants and their lawyers packed an appellate courtroom as they sat in dozens of chairs set up in front of the judge.

During a past detention hearing, Morehead accused one of the defendants, Samuel Villeareal III, 31, of supplying marijuana to unnamed Kansas University men’s basketball players during the 2010-2011 season.

The indictment in the case does not mention Morehead’s allegation about KU players, and it did not come up at Monday’s hearing.

Villeareal also has Lawrence ties, according to court records, and in one count he’s accused of attempting to distribute marijuana in May 2011 within 1,000 feet of West Middle School, 2700 Harvard Road.

Besides Dahda and Bauman, Grissom’s office has listed these Lawrence defendants:

• Roosevelt Rico Dahda, 30.

• Sadie Jolynn Brown, 25.

• David James Essman, 35.

• Mark Lee Romero, 31.

• Daniel Mark Sieber, 31.

• Carey Lynn Willming, 36.

• Jacob Paul Forbes, 30.

• Adam Christiansen, 31.

• Ryan Kearns, 24.

Because of the complexity of the case, including authorized wiretaps of phones and extensive video surveillance, prosecutors are asking a trial in the case not begin until next June. In a motion about the proposed timetable, prosecutors also said they anticipate “additional individuals will be indicted in this case in the future.”