PRINCE GEORGE'S COUNTY, Md.--A frail-looking 15-year-old boy weighting little more than a hundred pounds sits silently, hands folded in his lap, wearing that pensive look of desperation reserved by most adolescents for such crises as going out on the first date or getting caught sneaking a couple of dollars out of dad's wallet.

But this particular youth is not preparing to face his first girlfriend or an angry parent. This boy's desperation is terrifyingly real as he sits in Prince George's (P.G.) County Courtroom facing charges of murdering two policemen.

The mere mention of his name, Terrance Johnson, is enough to ignite an already explosive situation. You see, Johnson is black, the two slain policemen were white, and any Maryland resident will tell you that the most notorious features of P.G. County are its ultra-tense race relations and its controversial police force.

Rumors of a flourishing Ku Klux Klan chapter abound, and black residents often complain about what they see as police harassment and terrorism.

Blacks say Johnson was only defending himself against police abuse. White residents, on the other hand, say the shooting is an open-and-shut murder case and Johnson must be punished.

Police also claim the black community is using the case to stir up trouble and rekindle long-dead issue involving the police and the county's black residents.

P.G. County, although the largest county in Maryland, seemed more like a small town on the first day of the Johnson trial, which was slated for jury selection.

The county called in all 300 prospective jurors, a handful of whom were black, for the "event." As they filed into the courtroom, many greeted each other by name like old friends and chatted about the last case they had worked on together. "It sure is good to see the old faces," one said. "I'm looking forward to having another party like last time," commented a second.

Many spectators in the courtroom clustered near the windows to listen to the pro-Johnson demonstrators outside beating drums and chanting "Free Terrance" and "We say no to police brutality and racism." The court clerk swooped down on them, chastising them like wayward children to "Keep away from those windows; the blinds are closed for a reason." The whole event reached a sort of anti-climax with the announcement of a delay in the trial because the defendant had changed his plea from self-defense in both shootings to self-defense in the first and temporary insanity in the second.

Although the trial may be postponed, the controversy surrounding the case continues to polarize the community and intensify age-old strains and conflicts.

P.G. County was one of the largest and last strongholds of slavery. Only six years ago did the Justice Department force the county to desegregate its schools, and then in the midst of heated racial clashes which are far from cooled down.

The P.G. County police have traditionally projected an iron-fisted, shoot-first-ask-question-later image. Within a four-week period last year, white P.G. policemen fatally shot two unarmed black suspects. In nearby Washington, D.C., it is a standard warning that you don't venture into PG County unless absolutely necessary, and never at all after dark. "The police there don't take kindly to intruders, and they keep their own blacks squarely under thumb," as one black D.C. resident who used to live in P.G. County put it.

It was in this racially charged atmosphere that Officers Albert M. Claggett and James Brian Swart arrested Terrance and his 18-year-old brother Melvin on suspicion of rifling laundromat coin boxes.

Both brothers were taken to the Hyattsville police station, where they were put in separate rooms, ostensibly for fingerprinting purposes. Half an hour later no one had yet been notified of the boys' predicament. What happened next is unclear.

Police allege that Terrance ripped Claggett's gun from his holster while the two were alone in the small processing room, shot and killed him, and then shot Swart as he ran towards the room. Melvin, who was handcuffed to a bench in another room, claims he witnessed the officers beating his brother just before the shootings occurred.