NEW YORK -- "We're lowlifes as far as they're concerned," Joe Marino said in an urgent tone of voice. "Of course, I'd like to have their money. But the common person is beneath them. I'm not envious of that."

Marino, 38, leaned forward in his chair, intent. He wore a revolver -- government issue, like the sparsely furnished lower Manhattan office in which he sat.

Marino is a U.S. postal inspector assigned to the Wall Street securities fraud unit. For much of the past year, he and his handful of colleagues have been central players in the financial corruption investigations that have shaken Wall Street to its foundation.

The people Marino referred to as "them" are the investment bankers and lawyers who are targets, witnesses and counselors in the continuing probes -- well-educated and sometimes brash men, many of them in their thirties, many of them millionaires.

"They think differently than we do," Marino said. "I don't want to think like that."

"While all of us wouldn't mind hitting the jackpot -- like Joe says, even a couple hundred thousand would pay some bills," added Jim Pinorsky, one of Marino's partners, from across the room. "All their smarts and stuff didn't seem to help them. They just abused it."

"Their attitudes don't change," Marino said emphatically when asked if some of the former Wall Street superstars he has come to know have been humbled by their convictions on insider trading charges. "They still feel in talking to us that they're above us."

"They still have the bravado and contempt," added Pinorsky.

Postal inspectors Marino and Pinorsky, who began their careers as letter carriers, describe in the voices of what they call the common people a drama that sometimes seems to be played by and for the elite of American law and finance.

They are voices rarely heard, characters barely seen, in a corruption investigation characterized by waves of intense publicity and instant celebrity. In the Wall Street drama of Boesky and Levine, Guiliani and the SEC, the U.S. Postal Inspection Service, one of the main investigative agencies involved, has gone largely unnoticed.

The inspectors' anonymity is partly a product of their investigative franchise, which does not ordinarily carry them into the public spotlight. The insider trading probes focusing on the use of confidential information about corporate takeovers to make illegal stock profits has been coordinated by the U.S. attorney's office in Manhattan and the Securities and Exchange Commission in Washington.

All public announcements about cases have been issued by the U.S. attorney or the SEC. While the U.S. attorney frequently has noted the contribution of the postal inspection service and the Internal Revenue Service in its press releases, the role of the postal inspectors has rarely made press reports.

Generally, the postal inspection service provides security for the mails, probes mail theft and assists federal prosecutors with investigations into pornography, bombings and mail fraud. The mail fraud responsibility has drawn the service into the center of the Wall Street corruption probes.

Mail fraud is a catch-all federal law that prosecutors frequently use in white collar crime cases. Under the law, any attempt to use the mails in a scheme to defraud is a federal crime. Since most financial deals involve the use of the mails, the statute applies to a wide range of possible financial crimes.

The postal inspection service may not have the panache of the Federal Bureau of Investigation, but the work of the Wall Street unit has its own special appeal. Investigations have been carried out by as many as four inspectors working nearly full time since investment banker Dennis B. Levine's arrest in May 1986, said Jack Ellis, the Wall Street unit chief who has worked for the inspection service since 1971.

(Levine pleaded guilty to insider stock trading charges; his cooperation netted former stock speculator Ivan F. Boesky. Boesky's cooperation, in turn, led to guilty pleas by merger specialist Martin A. Siegel and brokerage executive Boyd L. Jefferies. Boesky, Siegel, and Jefferies are key witnesses in the continuing grand jury probes.)

The three inspectors who make up the Wall Street unit -- Ellis, Pinorsky and Marino -- are engaged in two massive grand jury investigations. One concerns allegations about the investment banking firm Drexel Burnham Lambert Inc. and its role in corporate takeovers; the other involves insider trading allegations against three leading Wall Street executives.

The postal inspectors often are called upon to interview executives who are witnesses in the probe. Sometimes they walk away from those meetings with impressions about matters other than insider trading.

"They'll spend more for a tie than we'll spend for a suit," Ellis said.

"If I go away with my wife and kids for the weekend, I might spend $300 or $400," Marino said. "One guy went away and the cost of a room per night was $750, and it was no big deal to him."

The postal inspectors do the same type of work that FBI agents handle in other criminal investigations. They make arrests, conduct searches, analyze records, locate and interview witnesses, and otherwise dig out information for the prosecutors in charge of the case. The inspectors have the capability of wiring an informant and eavesdropping on conversations, or installing listening devices in homes and offices.

On the morning of Feb. 12, inspectors Marino and Pinorsky arrived at the stately Wall Street offices of Kidder, Peabody & Co. to apprehend Richard B. Wigton, a Kidder vice president. Down the street, at the 85 Broad St. headquarters of Goldman, Sachs & Co., Ellis arrived with a fourth inspector to arrest Robert M. Freeman, a Goldman partner.

Freeman and Wigton, along with Timothy L. Tabor, a former Kidder trader who had been arrested the night before, were charged with participating in an insider trading conspiracy. Quickly, however, public attention focused not on whether the men were innocent or guilty, but on whether it was proper to arrest Freeman and Wigton at their offices, in full view of their colleagues, rather than calling and asking them to turn themselves in to the U.S. attorney, Rudolph W. Giuliana.

Arresting suspected criminals "is taboo down there," said New York postal inspection service head John Slavinsky, a trace of irony in his voice. "They don't contemplate something like this happening in lower Manhattan."

Accounts of the arrests noted that Wigton was led away in handcuffs while his longtime Kidder colleagues looked on stunned. One newspaper even reported that Wigton was in tears after being informed about the warrant for his arrest.

The postal inspectors who made the arrests make no apologies. They pointed out that the procedures used were routine and that there was concern by investigators that Freeman and Wigton might flee or destroy documents crucial to the case if they were given advance warning of the arrests.

Ellis said his inspectors arrest people the same way "whether it's the president of the United States or John Doe out here on the street." But Ellis and his colleagues are eager to set the record straight on a couple of points.

They said that contrary to some accounts, both Freeman and Wigton were handcuffed, in keeping with standard inspection service arrest procedure. While it was reported that only Wigton was shackled, the inspectors said Freeman was handcuffed as well, but not until after he had boarded the elevator and was no longer in view of his coworkers.

In addition, neither Pinorsky nor Marino said they can recall Wigton crying, though they said he was visibly shaken when informed of his arrest. Pinorsky recalls that he took Wigton into the executive's office to allow him to calm down while the arrest was explained and his rights outlined.

A little-known factor that has hampered the continuing investigation of Freeman, Wigton and Tabor was the death in May of postal inspector Robert Paschel, 41, who worked in Ellis' Wall Street unit. Paschel, who exercised regularly, died of a heart attack while using a rowing machine in a gym at the Church Street post office building where the securities fraud unit is located.

Paschel's death has disrupted the prosecutors' investigation of cases against the three executives. An accountant with long experience in securities fraud cases, Paschel was expected to be a key prosecution witness against the men. For months, Paschel had sat before a personal computer in his office, typing in data, analyzing stock trading records and preparing chronologies of takeover events. When he died, much of that work went with him.

"The bottom line is that he could get up and testify before the grand jury or in court as an expert," Ellis said. "He would have been the main person testifying about records."

Now Paschel's partners are trying to shoulder the burden. There are several openings for inspectors at the Wall Street unit, but Ellis said that filling the positions will take time. One problem is that few inspectors want to transfer to New York. They find it hard to live in or near Manhattan on their salaries.

Most of the prosecutors who work in the Manhattan U.S. attorney's office are just passing through -- the average stay for an assistant U.S. attorney is six or seven years. Many of them then join their law school colleagues in lucrative private practice. The same is largely true at the SEC in Washington. The attorneys are prosecutors one year, defense lawyers the next.

But the postal inspectors appear to be in it for good, or at least until they qualify for their pensions.

They are not too impressed with the historical significance of their work. Asked to assess the causes of Wall Street's worst scandal in 50 years and to describe the motives of the high-flying financiers who have been implicated so far, the inspectors respond succinctly. "The crime pays," Marino said.

As for the fallen executives, tainted millionaires and one-time whiz kids he has met during the probes, Pinorsky was equally curt: "I kind of thought they were stupid."