Paul P. Pomponio, 65, one of three brothers who headed a multimillion-dollar realty and construction empire that was mired in legal troubles in the early 1970s, died Aug. 22 at his home in Fairfax after a heart attack.

Mr. Pomponio, his brothers, Peter and Louis, and their partner, Charles J. Piluso Jr., headed the Pomponio Brothers Realty & Construction Co., a conglomerate of construction and real estate management firms that built about 15 high-rise offices and apartment buildings in the Rosslyn section of Arlington and Washington in the 1960s.

They were responsible for the early commercial development of Crystal City and the Arlington County waterfront, drastically altering their skylines. They replaced a succession of gasoline stations and decaying buildings with glittering new office buildings along the Jefferson Davis Highway corridor. They also built a number of high-rises in Rosslyn, including the 14-story Pomponio Plaza, which was later sold to a nonprofit Washington charitable foundation.

Before crumbling in 1972 under tax and financial investigations, the conglomerate, which grew from a plumbing supply business in Arlington, employed 2,000 workers in 46 family-owned corporations. At the time, it was the largest real estate and construction complex in the Washington area.

The brothers' troubles began in 1972, when their finances and taxes came under investigation. Their creditors seized some of their vast holdings, and the empire shrank. All four were convicted of fraud in 1974, but the convictions were overturned by the 4th U.S. Circuit Court of Appeals. In 1975, the appellate court also overturned tax fraud convictions against Paul Pomponio, his twin brother, Peter, and Piluso.

The three brothers were reindicted in 1976 and went on trial for a second time on federal fraud charges. In the second trial, Piluso testified against the brothers. The brothers were acquitted of bribery and mail fraud charges, but Paul and Peter Pomponio were found guilty of tax fraud.

Paul Pomponio, who was born in Plainfield, N.J., grew up in Arlington, where he graduated from Washington-Lee High School. He attended the University of Richmond and George Washington University. He served two years in the Army in the late 1950s.

His marriages to Judith Brocksmith and Nina Vosburg ended in divorce.

Survivors include his companion, Betty Costello of Fairfax; two daughters from his second marriage, Cheryl Hodges of Roanoke and Laura Vosburg of Fairfax; a sister, Gloria McKeever of Centreville; two brothers, Louis J. Pomponio Jr. of McLean and Peter P. Pomponio of Rockville; and six grandchildren.