Former massage parlor operator Louis Michael Parrish And his top assistant have told investigators they paid $500 a month to former Alexandria chief prosecutor William L. Cowhig between 1976 and 1978 to avoid prosecution, according to three separate accounts.

Parrish, 33, who recently testified for four hours before a federal grand jury investigation alleged corruption of public officials in Alexandria, gave the information to prosecutors after he was convicted in March in U.S. District Court of prostitution and racketeering charges, according to reliable sources.

His top aide, Larry J. Wadino, also convicted last March on prostitution related charges, has given the same allegations to other investigators, The Washington Post has learned.

In addition, former Virginia House Majority Leader James M. Thomson told federal officials in December that he unexpectedly was given the same account during a meeting in his Alexandria office with two lawyers, sources said.

The original agreement to make the cash payments to Cowhig, according to sources, came about in late 1976. Parrish, Cowhig and Alexandria attorney James I. Burkhardt, who was Parrish's lawyer at the time and a key figure in Parrish's massage parlor business, allegedly met in a crystal City hotel room to arrange the monthly payments, sources said.

The meeting reportedly took place as Parrish was planning to move his prostitution business from Arlington, where he had been successfully prosecuted, to Alexandria.

According to federal officials and court testimony, Parrish's network of massage parlors and "out call" prostitution services was able to flourish in Alexandria until May 1978, grossing more than $1 million a year.

Cowhig, 45, and Burkhardt, former president tof the Alexandria Bar Association, are known to be subjects of the current grand jury investigation.

Cowhig, who resigned as prosecutor Febuary 23 and has since move to Daytona Beach, Fla., to run a bakery, could not be reached for comment. His longtime administrative assistant, Mary Ann (Sam) Pastorek, answered a call to the bakery yesterday and denied the bribery allegations on Cowhig's behalf.

"Bill's never even met the bum," she said, referring to Parrish.

Burkhardt at first declined to comment on the allegations that he had met with Cowhig and Parrish in Crystal City in 1976. Later, he said that in "early 1975" he and Cowhig were having lunch in a restaurant in Crystal City when Parrish came by. Burkhardt introduced Parrish to Cowhig as a client, but "the subject of massage parlors never came up," he said.

Burkhardt yesterday called the payoff allegations "completely inaccurate."

Parish has not been granted immunity, according to one federal source. However, it was understood that Parrish's cooperation in testifying before the grand jury meant that no charges would be brought against him in connection with payoffs to a public official, the source said yesterday.

The grand jury is investigating possible links between parrish, Burkhardt and Cowhig. Already, Cowhig has turned over to the grand jury finacial records and documents. Sources said last week that the investigation is now concentrating on the tax aspects of the case.

Cowhig was indicated a year ago this week on felony bribery and illegal gambling charges stemming from a state investigation into the city's bingo scandal. He was acquitted of taking $32,000 in bribes from the operator of the city's most lucrative bingo games in exchange for overlooking possible violations in the games.

Cowhig was also acquitted of illegal gambling charges in connection with a separate bingo operation in Alexandria. Rather than face a second illegal gambling charge, Cowhig agreed to resign from his $42,500 a year office Feb. 23. Cowhig had first been elected commonwealth's attorney in 1973. Two weeks before the resignation, a special prosecutor was appointed to investigate allegations that Cowhig solicited a sexual favor from the wife of a defendant in exchange for leniency. Cowhig's was eventually cleared of any wrongdoing, but the Virginia Bar Association began its own investigation of the matter. That probe is reportedly continuing.

Federal prosecutors, who refused to comment on the current grand jury investigation, learned of the Parrish Cowhig payoff allegations as early as last December, according to sources.

This was when Burkhardt and Alexandria attorney Leonard B. Sussholz, one of Cowhig's defense lawyers at the bribery trial, visited James M. Thomson at his North Washington Street office. The purpose of the meeting, sources said, was to enlist Thomson's help as an intermediary in contacting special bingo prosecutor Edward J. White.

According to sources, Thomson was to be asked to persuade White to drop the remaining charges against Cowhig in exchange for Cowhig's resignation.

During the meeting, Thomson was reportedly told that Cowhig had been receiving regular $500 cash payments from Parrish.

Thomson did not go to white. Instead, he turned over the information to then U.S. Attorney william B. Cummings, sources said.

Thomson confirmed the meeting this week, but declined to discuss the subject matter. Thomson did say the meeting was called to discuss "a problem in the commonwealth's attorney's office" and said Burkhardt and sussholz "were looking for advice. I wouldn't characterize it as legal advice."

At the time, thomson was embroiled in a bitter debate over his candidacy for an Alexandria Circuit Court judgeship. "I didn't tell them [burkhardt and Sussholz] I was going to the U.S. attorney's office," Thomson recalled.

Asked why he did not contact local prosecutors, Thomson replied, "Bill [Cowhig] was still the commonwealth attorney. Certainly I didn't talk to that office."

Cummings, now in private pratice in Alexandria, declined to comment this week on the payoff allegations.

One source said this week the alleged payoffs reportedly stopped in May 1978 when the FBI conducted a massive midnight raid on Parrish's Alexandria operations, seizing truckloads of documents.

Parrish, described by the FBI as a reclusive entrepreneur who carried a 357 magnum in his briefcase, was convicted in Alexandria federal district last March on 9 counts of prostitution and racketeering charges. Parrish was sentenced to five years in prison and is currently free on bond while he appeals the conviction.

Testimony at Parrish's trial characterized Burkhardt as a close associate who played an integral role in the massage parlor operation from 1975 to 1978.

According to court testimony, Parrish told an associate that he wanted to have "the best damn whorehouse in Alexandria."

Two former Parrish top lieutenants told a reporter last year that Parrish dreamed of establishing a "sex and pleasure" empire in Alexandria, including bingo games, numbers rackets and a VIP travel agency.

The employes told a reporter that Parrish often boasted of being "inviolate" from prosecution. According to a former masseuse, an alexandria police cruiser pulled up outside a Parrish-owned massage parlor one night, its red lights flashing.

The woman said, "None of the cops came in, but everyone was really scared. Parrish said, 'Don't worry. I'ill take care of that.' The cruisers never came back again." CAPTION: Picture 1, James M. Thomson . . . meeting in his law office; Picture 2, James I. Burkhardt . . . denies bribery allegations; Picture 3, William L. Cowhig . . . subject of grand jury probe; Picture 4, Louis Michael Parrish . . . ex-operator of massage parlors