Nicholas Soussanin, 50, who was shot to death Friday afternoon while chasing two robbers who had held up an auto parts store in Bladensburg, was a resident of District Heights and president of the Nekoosa Contracting Corporation, a landscaping construction firm.

Prince George's County Police said Mr. Soussanin was in the Martin and Otterback Automotive Parts Machine Shop at 4814 Upshur St., when two men produced a gun and demanded money from the establishment. After taking an undisclosed amount of cash, the two men fled. Mr. Soussanin, who was not robbed, pursued the gunmen, and one of them turned and shot him, police said.

Mr. Soussanin had started Nekoosa Contracting in New York in 1954. The company has been located in District Heights since 1975. Among the projects on which it had worked were the Smithsonian Institution's Air and Space Museum, the Kennedy Center for the Performing Arts and the U.S. Courthouse in Washington.

Mr. Soussanin was a native of Hollywood, Calif. He lived in Ohio and New York before moving to the Washington area in 1971. He served in the Navy in the early 1950s.

He was a member of the St. Nicholas Russian Orthodox Church in Washington. He was a member of the Moose, the Kiwanis Club and the American Legion.

Survivors include his wife, Tanya, of District Heights; three sons, Christopher, of Temple Hills, Nicholas, of Houston, and Michael, of District Heights; a daughter, Natasha, of District Heights; a half-brother, Nicholas Saunders of New York City; two half-sisters, Tanya Smith of Fort Lauderdale, Fla., and Stamford, Conn., and Irene Arnoldoff of Los Angeles, and one grandchild.