The food stamp fraud trial of State Sen. Tommie Broadwater Jr. (D-Prince George's) and four codefendants opened today in federal court here as prosecutors and defense lawyers sifted slowly through a list of some 70 prospective jurors.

No jurors had been chosen by the end of the day, and presiding Judge Norman P. Ramsey excused the panel. Jury selection is expected to be completed Friday with opening statements by lawyers in the trial, expected to last two weeks, to begin Monday.

Broadwater, 41, looking subdued as he sat in the courtroom with his defense attorney, R. Kenneth Mundy, is charged with laundering $70,000 in illegally obtained food stamps through his Chapel Oaks Farmers Market in Fairmount Heights.

Also charged in the case is Broadwater's daughter, Jacqueline, 21, accused of doctoring the books of the farmers market to conceal the illicit origin of the food stamps. In addition, three Broadwater associates, William Dudley, 49; Raymond Quigley Sr., 68, and his son, Raymond Jr., 49, are charged with buying $70,000 in marked food stamps from an undercover Secret Service agent. The three men are accused of buying the food stamps at 40 percent of their face value from the agent and then transporting them to Broadwater.

Broadwater is accused of paying Dudley 60 percent of the face value of the stamps and then laundering them through his market for redemption from the government at their full value. Broadwater and the other defendants repeatedly have said they are innocent.