James W. Cahoon, a senior systems scientist at Computer Sciences Corp. for nearly three decades, died July 1 at MedStar Georgetown University Hospital. He was 78.

The cause of death was liver and renal failure, said his wife, Ann Tracy Cahoon.

Mr. Cahoon, a Gaithersburg resident, retired from Computer Sciences in 2003. Early in his career, he was a senior computer scientist at the National Security Agency and Control Data Corp.

James Wells Cahoon was born in Green Bay, Wis., and received a bachelor’s degree in mathematics from American University in 1960.

After graduation, he worked as a computer scientist at NASA’s Goddard Space Flight Center in Greenbelt, where he contributed work to the Orbiting Geophysical Observatory satellite program.

He was a longtime resident of the Luxmanor community in Rockville before moving to Asbury Methodist Village in Gaithersburg in 2012.

Survivors include his wife of 49 years, Ann Tracy Feick Cahoon of Gaithersburg; a brother; and a sister.

— Megan Mcdonough