A U.S. investigation into labor - management racketeering in the Washington suburbs is focusing on allegations that a Washington Construction firm helped a former local Teamster official obtain an expenssive home in return forn special treatment from his union on multimillion-dollar construction contracts.

The extent of the federal probe came to light after construction executive Rpbert Lee Miller, who was regarded as a potential witness in the investigation, was murdered in a Rockville motel Tuesday night.

Montgomery County police investigating the murder say that they have no firm clues about the motive. The dead man's son said in an interview with The Post that his father was concerned about recent difficulties he was having attracting work because of his firm's nonunion status.

Miller's difficulties coincided with the stepped-up pace of the labor-management racketeering investigation by the U.S. attorneys office in Baltimore, which recently subpoenaed Washington-area union and construction firm records covering the years 1972 to 1975, according to union and construction industry sources.

According to labor sources, the allegations under investigation fit a pattern of labor-management "sweetheart" deals elsewhere in which labor officials have received money or gifts in return for assuring low wages, an absence of labor strife or strides or the avoidance of union interference in nonunion projects.

In the current federal probe, investigators are looking especially at events surrounding the multi-million-dollar construction of new lanes on the Virginia portion of the Capital Beltway by one of the area's major road-building firms, Excavation Construction, Inc., and an associalted firm and subcontractor, Interstate Bridge. Miller was president of Interstate Bridge until he was murdered. The president at that time of the local Teamsters union, to which truck drivers working on such projects belonged, was Frank DeBrouse.

In 1973, DeBrouse, who until last year was president of Washington's

Teamsters local 639, moved into a large, contemporary home constructed in Anne Arundel CountY by Lyon Builders Inc., whose president is listed in corporate records as John W. Lyon. About six months later, DeBrouse signed a contract with another, much larger firm Lyon headed - Excavation Construction Inc. - the firm working on the Beltway. The pact set the hourly wage for union drivers at $2.50 less than the prevailing scale.

Set on 2.57 acres in the exclusive "Tara" section of Davidsonville in Anne Arundel County, the DeBrouse home has a swimming pool on its grounds and a path that leads to tennis courts, The building permit was issued for a home containing 2,850 feet of floor space with three bedrooms.

County records show the material and labor for the home alone cost $60,000 in 1973. The lot was pruchased for $16,000. Also, a $100,00 nine-month loan was taken out for the construction.The home's present value is estimated at more than $20,00.

The home and the contract DeBrouse signed with Lyon's Excavation Construction Company steeing low truck driver wages for work on the 22 mile widening of the Beltway in Virginia became part of a seven-year union battle that ended with DeBrouse's ouster as local president by insurgent union members.

DeBrouse could not be reached for comment over the past two days. Lyon was also unavailable for comment as were lawyers for both men.

The federal investigation actually began over a year ago when U.S. investigation actually began over subpoinaing records of Baltimore's Teamsters Local 311, according to labor sources. The subjecto of the probe then, sources said, was the union's pension and health and welfare fund in Baltimore and Washington.

Miller often was seen in the company of DeBrouse and a Baltimore Teamsters official, laboir sources said, and once helped the Teamsters organize race track exployes in the Baltimore area by showing up in a helicopter at a Teamster meeting.

The owner of about 30 thoroughbred racing horses, Miller also was a familiar figure at Maryland's mile racing courses, especially pimlico. He not only owned racing horses but bet heavily on races, usually at the $50 windows.

It was part of a high rolling lifestyle supported by his rapid climb up the ranks of the construction world.

One key to the union-management arrangements now under investigation, according to labor and other sources, is the subcontracting work done b Miller's Interstate Brdge, for John Lyon's Excavation Construction. A Maryland attorney who once represented both firms said yesterday that the two companies had a "dual shop," meaning the two worked together, one unionized and the other nonunion, to keep labor costs down and bid as low as possible for construction jobs - the practice is called "double-breasting.

According to Washington Metro Subway Construction records, Excavation Construction, Interstate Bridge, or a Subsidiary bid on the same contract three times and one of them always won.

Miller's Interstate Bridge won more than $5.7 million subcontracting work on the widening of the Beltway in Virginia from Excavation Construction, according to Virginia records.

Excavation Construction Inc. won two of the three major construction contracts for the Beltway widening - contracts that totaled $45.9 million. Excavation Construction now is working on part of the I-66 highway extension from Front Royal to Warrenton.

Construction sources who worked on the Beltway extension project remember Miller's flamboyant presence on the job. "You have to be playing with some strange people to show up at a construction site in a chauffer driven limousine," one said of Miller.

David Weinberg, attorney for Miller, confirmed yesterday that all the records of Interstate Bridge had been subpoenheed by the U.S. attorney's office in Baltimore six months ago. Weinberg said that, as far as he knew, Miller's personal racords had not been requested.

Another informed source said the Internal Revenue Service had performed a recent special audit on Miller covering some of the years in question.

A top Labor Department official familiar with labor-management racketeering also confirmed that he had been contacted by investigators this past month in connection with the federal probe.

The subpenas issued have asked for all records of the unions and firms contacted, a "shotgun" approch to examine all the complex dealings between the Baltimore and Washington Teamsters locals and the firms headed by Lyon.

Lyon also is vice president and general manager of Parking Management, Inc., Washington's largest parking lot and garage operation, headed by millionaire developer Dominic J. Antoneli Jr. Antonelli was recently indicted with D.C. mayoral aide Joseph L. Yeldell on briberycharges. CAPTION: Picture 1, Frank DeBrouse's Davidsonville home, showing swimming pool and tower lights for the tennis courts. Home is valued at $200,000 on today's market, By James M. Thresher - The Washington Post; Picture 2, Frank DeBrouse once headed union, 1972 photo; Picture 3, ROBERT LEE MILLER . . . slain in Rockville motel; Picture 4, JOHN W. LYON . . . firm built palatial home.