The disgruntled detective slouched in his chair in alocal police department, his arms folded across his chest. "Take a good look," he said cynically, using his chin to motion toward the detective bureau, "it may not be here in five years."

The detective admitted he was exaggerating a bit, but he betrayed the apprehension many police investigators feel about their future as their administrators have begun to re-evaluate the need for a large force of detectives.

"It's one of the most heavily debated topics in law enforcement today," says Fairfax County Commonwealth's Attorney Robert F. Horan Jr., referring to the controversy over whether detective work should become more specialized or be more diffused throughout the total police force.

The debate was fueled in large part by the release two years ago of the "Rand Report." Nicknamed for the California corporation that carried out the research, the report concluded that investigators spend only "about 7 per cent of their time on activities of patrol officers, members of the public, an routine clerical processing more than investigative techniques."

Most recently, the report's conclusions were bolstered by the widely publicized apprehension in New York of the man alleged to be the killer known as "Son of Sam."

Despite a 300-detective task force working exclusively on discovering the killer. tips from three citizens and the routine work of a patrol officer - a parking ticket - actually led to the arrest of David Berkowitz. As former New York City deputy police commissioner-turned-novelist Robert Daley wrote in a recent New York article, "In the end, a traffic cop did in fact trip over "Son of Sam."

In the Washington area when five women were murdered this year and last in Alexandria and Fairfax County, "key evidence leading to the arrest of a suspect was developed by a uniformed officer," according to the Fairfax police chief, Col. Richard A. King.

Detectives familiar with that case have different feelings. As Ronald Yeager, a nine-year investigator with the Fairfax police force, put it, "In that particular case, had it not been for previous knowledge and communications between other detective bureaus being shared, the case would still be open if left up to uniformed (police) officers . . ."

Commissioned jointly by the U.S. Department and Criminal Justice and the Law Enforcement Assistance Administration, the "Rand Report" suggested that local police departments re-allocate their resources "from investigative units to other units."

This shift would mean, according to the report, having a larger number of "generalist-investigators" on the uniformed patrol staff who would be more active in the initial investigations of crimes and in follow-up work.

"The resources needed to field generalist-investigators would be obtained by reducing the number of investigators," the report said bluntly.

The report did not advocate eliminating detective units completely, but instead recommended trimming what it saw as excess fat from the investigative units as they now exist and creating "Major Offenses Units" with highly trained and experienced officers for crimes such as murders, rapes and serious assaults.

Montgomery County Police Chief Robert diGrazia, who heads a force of 800 officers, agrees with the trend away from specialized detectives, which he called "the worst thing for police (work)." It is bad because it means "defining some duties too stringently so some men were sitting around while others were working hard," diGrazia explain

This became "a real problem in vice and drug control," diGrazia said. Patrol officers thought "they had to be in undercover work and look raunchy and have long hair (to solve) those crimes," he said.

DiGrazia recently launched an experiment aimed at decentralizing his detective headquarters and integrating his investigators more fully with patrol officers. A few detectives from each of the county's investigative units, such as juvenile and fraud, were assigned to the Silver Spring police office where they work as a team with patrol officers and are responsible for a limited area of the county.

The detectives then inform the patrol officers of all ongoing investigations in order to enlist their assistance. This type of organization, which can have many variants, is commonly called team policing.

Arlington County Police Chief Roy C. McLaren is another supporter of team policing, but he abandoned efforts to start it in Arlington because of opposition from within the detective unit and because it would have come at the same time as a cut in the county police force mandated by a shrunken budget, McLaren said.

McLaren who heads a department of 276 officers, said he did not want that cutback in services to be identified in the public's mind with team policing because "it's too good a concept to waste."

As the largest police department in the area, the District of Columbia's force is also the most specialized. Officials say the workload (more than 200 homicides investigated in 1976) requires such specialization and that patrol officers, who last year responded to more than 60,000 calls, are too busy to get further involved in investigative work on a routine basis.

Detectives tend to flinch at suggestions that patrol officers could do their jobs and at programs that interfere with their current method of operation. One detective describe as "hogwash" the idea that patrol officers could even find the time to do the paper work and follow-up on crimes that detectives must do.

"Everybody, doctors for example, is more specialized, why shouldn't we be?" Fairfax's Yeager asked. "Specialization is the only answer to crime," he added.

This view is echoed by the men with whom investigators often have closer relationships than they do with their own supervisors - local prosecutors.

Both Henry Hudson, Arlington's Chief assistant county commonwealth's attorney and Fairfax's Horan say that the skills of the specialized investigators are crucial to successful solutions and prosecutions of major crimes.

At a recent public hearing before Fairfax County's Civil Service Commission, Horan said, "I would not suggest that investigators are more courageous or more moral (than patrol officers) but whether we like it or not, investigative work is more complicated . . . There are certain parts of police work so complicated that it's ludicrous to take anyone in blue and ask him to do the job."

Speaking about a report published last June by Virginia's Council of Criminal Justice and the State Crime Commission, Horan said it "adopted a position I'm not too comfortable with (because it seemed to suggest there is too much specialization in police work."

Detectives say that besides the extra technical training they receive, there are other valuable assets they acquire on the job that patrol officers don't have the opportunity to cultivate. They cite the network of contacts and informants, the ability to interview suspects and experience in human interchange. "You learn people," said one detective.

As Arlington County detective described a colleague who specialized in solving child-molesting cases. "He's fantastic. He's able to talk to the kids easily and without even mentioning the incident the first few times, he is able to find out exactly what happened and then he knows who probably commited the crime. When he retires, we're out to lunch (in that type of investigations)."

Detectives also say that wearing plain clothes makes it easier for them to go into other jurisdictions and to approach people.

"Some people are afraid of uniformed men," said one detective. "Business people prefer plain clothes officers coming to their offices and other people like it because they don't have to worry about what the neighbors will think," observed another.