THIRTY-EIGHT . . . thirty-six . . . thirty-two," Howard Miller counts down the addresses as he slows, then stops the blue van in front of the number scrawled in his notebook. Persistent knocking, however, brings only the yaps of a chihuahua poking its face through the living room curtain. Miller peeks in the window, then pokes into the empty mailbox: "Never take the mail," he says, reciting what sounds like a line from the private detective's creed. "But always check."

Finally, abandoning the door, he strolls underneath the bedroom window calling, "Hello, hello," in a polite Virginia accent that lilts up in pitch as he rises on his toes attempting to peek in. "Yoo hoo . . . yoo hoo. Anybody home?"

Obviously not. So Miller leisurely snoops in the front yard searching for a lead. Traipsing across the lawn, he mumbles: "Why would anybody put a lawnmower there? . . . Looks like the house is kept . . . Uh huh, there's something funny about this, something psychological," he blurts, pointing to an abandoned Plymouth Fury alongside the driveway. "That's an old police car," he says, running his hand along where the siren and antenna were once attached. "There's something about a guy who likes to drive around in a police car. Sometimes they're overzealous and will say anything to get in good with police. It's like a guy who dresses up in women's clothes."

Aware that he may be extrapolating this clue a bit too far, Miller adds quickly, "But that's just an insight, a hint. Now I have to put that aside until I can prove something."

No signs are painted garishly on this businessman's van. "There's times to advertise and there's times not to," Miller says. "The sign of a great detective is no sign at all."

He's out to prove that two police witnesses could not possibly have seen his clients, the owners of a local disco, fleeing their financially ailing night spot just after it had been torched more than a year ago. Posing as an insurance investigator he intends to talk to the witnesses and somehow get them to say something that would indicate they could not possibly have seen what they told the police they had.

Meanwhile, the clients' attorney is in the judge's chambers arguing for an extension so Miller can have more time to find the witnesses. "Lawyers are the quarterbacks in the game we play," Miller says.

"You know, a private detective's license is really a license to hunt people," he says. "Everybody leaves a trail. Sometimes you lay in wait, sometimes you run your dogs and flush 'em out. It's not like cops and robbers, where you're using force. It's matching wits. It's a game."

Some see an element of sleaziness in private detective business. But Miller hardly fits the part. His indoor-outdoor sunglasses are prescription. He doesn't smoke, or drink and his greatest vice is coffee. At 33, his dark hair is cropped short and there's only a slight paunch creeping over the belt of his bright green, preppie-looking slacks. And on Sunday he counts the collection at the Methodist church.

Miller sees himself, and some 200 other area detectives, as the last line of defense for abandoned wives, children snatched in Kramer-like custody feuds, and businessmen who suspect their partners may be taking a little off the top. And once in a while, like Paul Drake of the "Perry Mason" series, Miller helps get wrongly accused defendants off the hook.

Miller and some law enforcement officials agree that police often lack the time, officers, jurisdiction and sometimes the clients' confidence to effectively resolve such matters. When this happens, the private detective, patrolling the gray areas around the perimeters of the legal system, may be called in.

The fully-loaded .38 special is precariously positioned on the dashboard and the Rotary club installation dinner he plans to attend later is pushed back in his mind. Today, at least this morning, the mundane chores of a small businessman are behind him. Miller is a private eye, sleuthing through Fairfax County. In Virginia anyone can carry a gun as long as it is not concealed, but a private detective's license, mandatory for operation in the area, does not grant any firearms privileges beyond those of any other citizen.

The two-way radio crackles on and off as he wheels the van onto Lee Highway out past miles of parking lots surrounding low-lying shopping plazas and drive-in banks. Miller sputters at the red lights and clogged traffic, but delights in relating the juicy innuendo connected to his case -- a smattering of drugs, bribery, vengeance and political favoritism. "We've got a real soap opera here," he says, exaggerating somewhat. "We've got a regular 'Who shot J.R.?' in its finest form."

Although he is not an insurance investigator or a policeman or a lawyer with a subpoena, Miller considers the investigation a means to a just end.

"Remember when you were little and your mother told you about the big lies and the little white lies? Well, we're lying," admits Miller, "but we're not criminals. I consider it a deception that's necessary.

"I look on the detective business as an industry which extends the rights of people. Everyone in life is not equipped to go around corners and look around. The detective becomes the eyes and ears of the people who aren't trained and can't really see what's going on around them. The information we collect assures a person's interests are safe, or in jeopardy."

Despite increasing no-fault divorce and insurance, Washington's detective businesses remain healthy because in deciding the amount of a settlement or the custody of children it is still necessary to prove one party was more at fault than the other. "When there are kids or money involved, no-fault goes out the window," says Miller. "Everyone is willing to settle, but the question is for how much?

"We're dealing with people who are crafty, devious and smart. They've all seen the TV shows and read the detective stories," Miller laments, launching into "war stories" of high-speed auto chases and phony names on the hotel register. "They're just being cautious. They know they have a lot to lose. But with persistence we wear them down. For every evasion there's a counter."

And so on a stakeout Miller is constantly changing his clothes, as well as the vehicle from which he observes hotel rooms, clandestine dinners and love nests throughout Northern Virginia. A favorite prop is the hard hat Miller keeps in the back of the van.

Imagination, he says, is the key to a successful stakeout.

Jack Cowan, one of Miller's employee's who sometimes works as a security guard, but who also works as an investigator says he has replaced light bulbs in dimly lit corridors to insure capturing just the right photo of a happy couple emerging from an apartment very early in the morning. Cowan said another investigator disguised as a cripple in a wheelchair spent the afternoon observing a suspect in a park.When the suspect left, the investigator simply stood up and walked away, to the amazement of those on surrounding park benches. And another time, Cowan brought his dog to an apartment building and began to snap pictures of it. "Of course, the dog was in the pictures," he said, "but so were the people" who were leaving the building together, very much together.

And rooting through a pile of trash to verify an address is just a part of the job for Cowan.

But the times for devious stunts are rarer and the minor fibs are more commonplace as Miller roams suburbia pumping information from neighbors, and sometimes his own friends, whom he cultivates with frequent visits while tracking leads in their neighborhoods.

"A lot of detectives are loners. They like to keep a low profile, says Miller, himself a very public private eye. He's in the Chamber of Commerce, the Rotary and is a past president of the Virginia Security Association. While hunting the witness he drops in to fish for information from the man who makes plastic signs advertising the bogus businesses that Miller attaches to his van as a disguise. The two men bemoan the state of free enterprise and sing praises of Ronald Reagan. Later, he gabs on the porch of a retired vice admiral who hires Miller to provide security for his estate. And the defense attorney in his current case is a friend Miller met at the polls during the 1977 Virginia governor's race. The lawyer was passing out Democratic literature; Miller, Republican.

"My business is my life. It's my work and my pleasure. I'm free to socialize with my friends and follow a lead however I want," says Miller who left the Army in 1969 and, like many private detectives, worked in local law enforcement, in his case for seven years. In 1976, however, he grew tired of being a "slave to the [police] radio" and started his private detective and security company, which brings in $200,000 a year.

His security work, which includes a contract to watch over SSTs at Dulles, accounts for approximately half of Miller's business and provides the steady income necessary to pay his 20 primarily part-time employes and maintain his office above the 7-Eleven at Loehmann's Plaza on sprawling Arlington Boulevard.

The Brew-Matic coffee machine burbles on the other side of Miller's desk.

Seated behind the desk he can look straight ahead at the file cabinets and cardboard boxes that hold notes and evidence of years of indiscretions. Or, he can swivel his chair around to glance out the window overlooking the shopping center's air-conditioning units that rise out of the gravel-topped roof. Beyond that, stretching out toward the horizon is suburbia.

"It's not much," Miller says of the office but adds, "The street is our office. That's where our efforts are plied."

There's a payroll to meet, a check to deposit, a bill for the answering service and a series of mundane details that never seem to distract Jim Rockford, Sabrina Duncan or other sleuths of television and the screen. Particularly annoying to Miller is his clients' tendency to grow forgetful when Miller's bill comes around. Passing a condominium development, he comments, "There's a guy in there owes me $1,000, a lawyer. I guess I'll have to sue him."

At times it's a sordid business as clients spill their dirtiest laundry into Miller's lap. "But I never judge these people," he says. "I'm just after the facts, then it's up to the lawyers and the courts."

His involvement in local business associations and politics, including an unsuccessful 1979 bid for Fairfax County sheriff, keeps Miller from slipping into what he calls the "cynical police syndrome." He and his schoolteacher wife, Judi, also get away from the late night phone calls from battered wives and men in the field by darting to North Carolina to "watch the fish jump."

And the radio in the van is tuned to a country music station: "I spend all day peeling the crust off people to see what makes them work, and I find this the most relaxing, most simple, least pretentious music.

"Washington is a real pressure cooker. Everyone's worried about their promotions and impressing the right people," he says. "That kind of tension just tears families apart. It's unfortunate it's so good for my business."

After striking out on the witness' front porch, Miller saunters up to the house next door. His lips move slightly as he practices the pronunciation of the witness' name until a young man answers the door. In a brief conversation Miller comes up with two facts he generously refers to as leads. It turns out that the witness is a boarder and, it seems, he does not drive. So much for the abandoned police car theory.

Back in the van, Miller swings past a group of girls twirling batons in the street, then, he turns into the parking lot of the burned-out disco. Stalking across the spot where the dance floor used to be, Miller again studies the angles of street lights and a high stockade fence. "Naw, he couldn't have seen anything. At least I don't think he could've seen anything."

But the eleventh-hour effort is pointless. A radio call to the office finds no message from the attorney. The trial -- and the prosecutor's witness -- went on as scheduled.

As it turns out Miller was pursuing a bad address anyway and the witness did not even live at the house. But the trial ended in a hung jury and Miller's clients went free.

"I was really happy about that," he said later. "A smoking gun and a body at your feet is one kind of evidence. But this was not the kind of evidence (the eyewitnesses were in disagreement) you want someone to go to jail on."

On his way back to the office, Miller stops at the bank, where he endures a Friday-afternoon lunch-hour line and reflects on the case and his job. "Sometimes this is real boring," Miller says. "But I'm idealistic. You may not always get the bad guys, but at least they know you're out there watching them."