She was 17, a Bethesda flower child who had brought with her a "beautiful mixture" of four kinds of marijuana and three of hashish, plus some cocaine.

"Tonight I'll be doing (using) some cocaine," she said, with an air of impunity, during last Wednesday's Jefferson Starship concert at Capital Centre. "Around here, I haven't seen too many being hassled.I guess when you get a ratio of millions of kids to one pig, I doubt they (the police) would get away with it or try to instigate something."

Her attitude was rooted in the reality of generally premissive attitude which Prince George's County and Centre officials have displayed toward drug use inside the arena.

Yet, even as she spoke, pausing to hand out flyers to two upcomingpro-marijuana rallies, undercover county police were moving quietly to arrest 19 persons, including five under age 18, on charges of selling PCP, cocaine, LSD, marijuana and hashish inside the area's largest arena.

It was the largest single drug bust at Capital Centre since the facility was built in the middle of a Prince George's cornfield nearly five years ago. Wednesday night's county and park police operation, involving 87 officers, dealt a blow to the Largo arena's reputation as sort of a suburban safety zone for the drug counter-culture.

"The Capital Centre has, from the outset, recognized its responsibility toward enforcing the law," owner Abe Pollin said last week in a formal statement. "We recognized then, as we do now, and as any realistic person must, that where there is a large assemblage of people, a few will attempt to stretch the bounds of people, a few will attempt to stretch the bounds of enjoyment beyond that which is proper and even be willing to break the law."

Capital Centre personnel, he said, have been directed for two years "to carefully screen all material brought into the Capital Centre, to confiscate any illegal material discovered, and to deny entry to the bearer of such substance."

Last week's arrests were executed with the knowledge and cooperation of security officials of the privately owned and operated arena. Arena personnel and county officials have been meetingmonthly since January on law enforcement and public safely issues.

Prince George's police both rank and file and the hierarchy, have long been deeply aware of the drug problem at the arena, particularly during rock concerts, according to an internal police study obtained by The Washington Post.

"There is widspread drug usage and sales occutting inside the Capital Centre without any enforcement of the laws," said the July 28, 1975, county and park polce task force report.

Even performers were violating the law "by smoking" marijuana on stage "and encouraging the audience to join them," the report found.

The problem, police say, is that they cannot enter the arena without specific knowledge that a crime is being committed. There has also been concern that the presence of many uniformed officers could spark violence. So the county police have largely limited their role to patrolling the parking lots and access roads.

Inside, law enforcement is basically left to the arena's private security force, mod-looking young men wearing "Capital Centre Fuzz" T-shirts who act, according to the report, primarily as bouncers to eject the unruly.

Last Wednesday night, as rock music blared from the stage below, the smell of marijuana hung heavy in the shadowy darkness of the arena's seats.

Two years ago this month, following a flurry of stories about marijuana at the Centre, arena owner Abe Pollin agreed to allow undercover narcotics police inside the arena.

According to Capt. James Fitzpatrick, head of the special operations division regularly assigned to the Centre, these police agents have worked quietly, buying drugs during rock concerts and then arresting the dealers sometimes weeks later at their homes.

Inside the arena last week the Bethesda flower child said she brings the drugs, because "You don't know what you're gonna get" if you buy drugs at the arena.

The brother of one person arrested that night and charged with selling drugs confirmed her skepticism. His brother was not selling PCP as police alleged, he said, in a subsequent phone call to The Post. His brother was selling parsley sprayed with cooking oil, instead of parsley sprayed with the drug, he said.