Robert C. Cantrell, 51, the treasurer and business manager of the Southern Seminary Junior College in Buena Vista, Va., since 1981 and a former executive assistant to former D.C. mayor Walter Washington, was killed July 8 when the car he was driving struck a bridge abutment on Rte. I-81 near Buchanan, Va.

A Virginia State Police spokesman said that Mr. Cantrell apparently fell asleep and lost control of his car.

Mr. Cantrell, who lived in Buena Vista, was born in Pound, Va. He graduated from Virginia Polytechnic Institute and earned a master's degree from the University of Virginia. He did further graduate work at Columbia and George Washington universities. He served in the Air Force from 1954 to 1956.

He was a teacher in Kentucky and New York before moving here in 1961 to work as a legislative assistant to former Rep. W. Pat Jennings (D-Va.) From 1964 to 1967, Mr. Cantrell worked for the Office of Economic Opportunity.

He served on former mayor Washington's staff from 1967 to 1977 and then joined the staff of the House Operations Committee. In 1981, he went to work at Southern Seminary.

Mr. Cantrell was a member of the board of the Washington Performing Arts Society and a past president of the Capital City Ballet Guild. He also was a member of the Friends of the Kennedy Center and the Friends of the Folger Shakespeare Library.

Survivors include his wife, the former Mary Kathryn Hueni, a daughter, Charlotte Anne, and two sons, Fitzhugh Lee and Robert C. Jr., all of Buena Vista; his mother, Tottie Cantrell of Pound; two sisters, Frances Roberson of Wise, Va., and Lena C. McNicholas of Houston, and two brothers, Michael L., of Pound, and David L., of Knoxville, Tenn.