For Lawrence (Boots) Pasco, the day at Charles Carroll Junior High School in Prince George's County was fairly routine.

A teacher had smelled marijuana smoke in a school stairwell and had a good idea of who was responsible. Pasco was informed and the student was called in for questioning.

Under Pasco's expert grilling, the student admitted to smoking pot but not in the stairwell. "I was smoking outside," he said, fingering someone else as the likely stairwell culprit.The second student was called in to Pasco's office. "No, not in the stairwell. I was smoking pot down by the gym," the student said.

Pasco never discovered who had been smoking marijuana in the stairwell, but the two confessions were reported to the principal and the students received the standard punishment, a short-term suspension.

Pasco, a retired officer with the Metropolitan Police Department, is part of a 40-man security force operated by the Prince George's County school sytem as one part of its continuing crackdown on drugs and other illegal activities in the schools.

While police in Montgomery County have made headlines with more than 200 drug-related arrests on or near school grounds since the fall term began, the Prince George's school security force has been cracking down on drug use - quietly - for the past several years. Each year, approximately 500 students are apprehended for drug-related offenses, most entailing the use or possession of marijuana.

"There cannot be an educator alive who is not concerned about the influence of drugs in school," says Peter Blauvelt, chief of school security and a former detective with the Metropolitan Police Department and special agent with Naval intelligence. "We're going to do everything within our power to make use of drugs on school property a high-risk activity.

"We just won't tolerate use of drugs in school. We will file a juvenile petition even for half a joint of marijuana, knowing full well that it is not going to get into court. We want to make an impression. We've found that some kids will use this as a reason for not getting involved with drugs, and as far as we're concerned, if this helps them resist their peer pressure that's fine."

Blauvelt, who has a criminology degree from the University of Maryland, became school security chief in March 1971 with a mandate from school officials to beef up the existing security department, which Blauvelt says was "strictly a broken window outfit."

Officials had become concerned over crime, violence and other illegal activity in the schools, and when Blauvelt took over there was no way to cope witt the problems or even to take a reading about how serious the problems were. At the same time, the school system had been accused by the NAACP of illegally operating a dual school system, and officials believed that eventually they would face court-ordered busing. (They did in January 1973.) It seemed prudent to have a sophisticated security operation to cope with the inevitable rumors that busing might bring occasional racial flare ups.

In the fall of 1971, Blauvelt started hiring the first of his security force by signing on eight "investigator-counselors." He sought people with law enforcement backgrounds who had worked with youths.

"I needed people who knew how to run an investigation, but I also wanted people who liked working with kids," Blauvelt said. "We are not all Father Flanigans. We don't all believe there is no such thing as a bad boy. We try to treat the kids fairly, but firmly and with a lot of love."

One of Blauvelt's first acts was to establish a uniform system of reporting incidents, so he would have an idean of the problems he was facing. By the 1977-78 school year, the system has become so sophisticated that the security force had logged 6,100 separate incidents, ranging from locker thefts to extortion, armed robbery and assault.

Three years ago in two separate incidents, two students were killed during arguments over $5 bags of marijuana, and the security force went after the drug traffic in earnest.

"It's very hard for educators to accept the fact that there has to be a security force in the schools," says Blauvelt. "But we're specialists just the way the reading teacher or the math teacher is a specialist. Our speciality is making sure that everyone else can do his job and that education can go on."

To carry out their assignments, the 40 investigator-counselors - 30 assigned to a specific senior or junior high schools and 10 assigned to several schools within a geographic territory - are instructed to maintain a high profile and to get to know as many students as possible.

Edward Spindler, for example, known to the students at High Point High School as Deputy Dog, spends most of his time patrolling lunchrooms, hallways and parking lots. A retired D.C. police lieutenant, Spindler came to High Point in 1973 after 20 years as a Washington police officer.

"By keeping a high visibility, I stop a lot of things from happening that I don't even know I've stopped," says Spindler.

Spindler estimates he knows, at least by sight, almost all the 2,400 students at High Point.

Even though his role does include enforcement duties, Spindler is able to maintain a good relationship with most of his students. After he had been at High Point only two years, the senior class dedicated the yearbook to him. Last year, when a group of outside toughs came up to the school and threatened to jump Spindler, they were pulled away by other students.

At Carroll, Boots Pasco is known to the students as Baldy or Kojak and, like Spindler, tries to spend as much time as possible where the students can see him. "I enjoy this immensely. I've enjoyed it ever since I've been here," says Pasco, who retired on disability after 15 years as a Washington policeman.

To supplement the security force and to cut down on after-hours school vandalism, officials in Prince George's have installed what Blauvelt describes as "one of the most sophisticated security alarm systems in the world." Essentially, the system is a series of motion detectors in each school building. The detectors trigger an alarm at a central point should anything in the building move after the last person has left and the system has been activated.

The system has proven to be successful in reducing school break-ins. Last year, the first year in which the system was fully operational, losses attributable to breaking and entering were $95,569. In 1975, before the system was in operation, the annual breaking and entering loss was $176,515.