Friday, in the Colonial brick courthouse of the tiny county seat in Upper Marlboro, Prince George's County State's Attorney Arthur A. Marshall Jr. started his daily round of conversations with reporters at noon. The interviews -- some over the telephone, some in his office, many under the hot lights of television cameras -- continued virtually nonstop until he pulled out of the courthouse parking lot that evening at 6:40 p.m.

It was a particularly heavy media day for Marshall, with reporters interested in getting any last bits of information about the Len Bias case before a county grand jury today begins the bulk of its confidential inquiry into the former University of Maryland basketball star's death on June 19.

Marshall, 55, who is running for reelection this fall, is a hard-nosed prosecutor who has been a symbol of law and order in the county and one of the area's fiercest advocates of the death penalty since he was elected state's attorney a quarter-century ago.

In the four weeks since Bias died of cocaine intoxication after collapsing in his College Park dormitory suite, Marshall has been making headlines almost daily, criticizing the athletic program and drug policies at the university and airing allegations of criminal activity by university coaches and basketball players.

Parceling out exclusive interviews to various news organizations over the past week, Marshall has been reported as saying, among other things, that as many as half the Maryland basketball players regularly used drugs, that coach Lefty Driesell could be indicted for obstruction of justice if he had advised players to clean up evidence of drug use in Bias' dorm suite, that investigators have evidence to prove that Brian Lee Tribble, a longtime friend of Bias, brought cocaine into the dorm suite the night Bias died, and that Marshall is investigating allegations that one player bet on a Terrapin game.

Among those most concerned about Marshall's statements to the news media are Bias' parents, whose attorney, Wayne Curry, said on their behalf last night that "each new story had caused them renewed pain and grief."

Curry said that James and Lonise Bias, who have not commented on the case for several weeks, protest "the constant leaking . . . and Marshall's trial by media" and believe that "speculation, innuendo and rumor belong in another forum."

"They can live with the tragedy of Len's death . . . " Curry said. "However, they are relying on the impartiality of the grand jury process to tell them what happened in that dorm room" where Bias collapsed.

Asked about criticism that his disclosures have prematurely tarred some of those under investigation, Marshall said last week: "All I'm doing is reporting basically what our evidence suggests."

Marshall was out of town last night and could not be reached for comment about the Biases' statements.

Many of those who have followed his 25-year career as county prosecutor say Marshall's outspokenness is no surprise given his reputation as a volatile, and sometimes controversial, maverick both in the courtroom and in the political arena.

By taking on the university and its basketball team, Marshall has gained publicity that many local politicians agree is certain to bolster his chances for victory in the Sept. 9 primary against Alex Williams, his first serious challenger in 14 years.

But it is a role fraught with political and legal risks. His constituents include some influential politicians and lawyers who, because of their strong loyalties to the university, are concerned that Marshall is in effect seeking to indict the school as a whole.

"Marshall sort of has a tiger by the tail here in that if he does not go forward with the case he'll be accused of a whitewash by one element," said Vincent Femia, a judge on the county Circuit Court and longtime friend of the state's attorney. "If he does go forward he'll be accused of making political hay out of it by another element. He's out on a mine field right now -- one step the wrong way and it'll blow up on him."

Attorneys for some of those under investigation said that their clients could be hurt unfairly by the unsubstantiated allegations coming out of the state's attorney's office. Alan Goldstein, attorney for players Terry Long and David Gregg, who shared a suite with Bias and were with him when he collapsed, said the wide-ranging grand jury probe is new territory for Marshall. "I'm not sure he's doing it right," said Goldstein. "It's an awfully public investigation."

But, added Goldstein, a longtime Marshall friend, "He's probably the most honest guy I know."

So far, county political observers say, Marshall's high profile in the Bias case can only have helped mute one of Williams' central campaign issues: that Marshall has been soft on drug prosecutions.

Williams, a Howard University law professor and a political novice at 37, is the first black candidate thought to have a chance at winning countywide office in Prince George's. He is supported by some of the top political leaders in a county that is expected to attain a majority black population this summer.

Williams said he believes that Marshall is deliberately feeding titillating rumors and allegations to the media each day to keep his name in the news.

"He's on the tube every day," Williams said. "I'm really out in the cold with all this going on. In terms of media attention, he's batting one hundred and I'm batting zero.

"Why has it taken this incident to wake up the state's attorney's office to the drug problem?" Williams asked in an interview last week. "Marshall is doing a sweeping investigation of the University of Maryland as if it is a new phenomenon."

The grand jury investigation, as outlined by Marshall, will probe the circumstances surrounding Bias' death and will include an overall examination of drug use on the Maryland campus -- particularly within the athletic program.

Marshall said he believes that the university has been overly permissive about drug use, with campus police arresting an average of only four students a year on drug charges. "I've had some people in the Terrapins Club say, 'What are you doing?' " said Marshall. "I'm doing what I think is right."

In one of the interviews he granted Friday, Marshall said his office probably would not have investigated Bias' death had there not been "all this cover-up and lack of cooperation" immediately afterward by some of Bias' teammates, by Driesell and by Bias' high school coach, Robert Wagner, all of whom are among 65 persons subpoenaed to testify this week.

Marshall's keen interest in probing the College Park campus, said County Executive Parris Glendening, is "extremely controversial" because many people believe that it will throw a harsh spotlight on drug problems at Maryland that are no worse than those at many universities. "The county is very protective and very supportive of the institution," Glendening said.

Rep. Steny Hoyer, a Democrat who represents the county in Congress and who, like Glendening, is supporting Williams in the primary, said he believes that Marshall is going public prematurely with allegations that surface during the investigation. "I think it would be better to comment on whatever facts exist after the investigation is completed," said Hoyer, who is a lawyer. "That's not necessarily Mr. Marshall's way of proceeding -- he's likely to say what he believes."

In 1972, the last time he faced a serious political challenge, Marshall also became a central figure in a case that received constant attention from the news media.

On May 15 of that year, just as the campaign season was heating up, a Milwaukee busboy named Arthur Bremer shot former Alabama governor and Democratic presidential candidate George C. Wallace and three other persons in an assassination attempt during a rally at a Laurel shopping center.

Bremer's weeklong trial that summer in Prince George's County Circuit Court made national headlines and became the most celebrated case of Marshall's career.