Kenneth Jay Koontz, a district sales manager for Sun Microsystems Corp., died of a brain tumor Saturday at his Ellicott City home. He was 45.

Born in Baltimore and raised in Clarksville, Mr. Koontz was a 1975 graduate of Atholton High School. He earned a bachelor's degree in computer science in 1979 from the University of Maryland and a master's from the Johns Hopkins University in 1985.

He worked for Westinghouse Electric Corp. and Digital Equipment Corp. before joining Sun Microsystems in 1992. He earned many awards for his work, and was named the company's District Manager of the Year in 1999.

Mr. Koontz was always willing to help relatives and friends resolve computer-related problems, family members said. He was an accomplished woodworker who liked building bookcases and chairs in his basement shop. He also traveled, and had visited Ireland, Australia and France with his family.

Mr. Koontz was a member of St. Louis Roman Catholic Church, 12500 Clarksville Pike, Clarksville, where a memorial Mass will be offered at 1 p.m. Saturday.

He is survived by his wife of 19 years, Mary Catherine Cochran; a son, Michael J. Koontz, and two daughters, Callie L. Koontz and Cara M. Koontz, all of Ellicott City; his mother, Louise Frances Koontz of Clarksville; a brother, Charles L. Koontz of Westminster; and two sisters, Kathleen Louise Becraft of Clarksville and Carol Ann Koontz of Odenton; and many nephews and nieces.