Ernest M. Buck Jr., a Washington-based research specialist with Interpol, the international cooperative police organization, and a former Arlington County deputy sheriff, died July 1 at his home in Arlington. He was 64.

The cause was brain cancer, said his wife, Patricia Burchett.

In 1990, Mr. Buck joined Interpol Washington, where his work revolved around security analysis, financial fraud, and compliance and training in the drug division.

He was a program manager in the Justice Department’s International Criminal Investigative Training Assistance Program from 1994 to 1998, then a research specialist in Interpol’s state and local liaison division. He took medical retirement in 2010.

Ernest Marvin Buck Jr. was born in Arlington. He graduated from Washington-Lee High School in 1966 and from American University in 1982.

After serving in the Army from 1969 to 1973, he was a deputy sheriff in Arlington from 1974 to 1985. He later served as a diplomatic security officer with the State Department.

From 1990 to 2012, Mr. Buck was chief of the Clarendon Volunteer Fire Department.

Mr. Buck was also a musician who played string bass in bluegrass groups and in German bands during Oktoberfests.

Survivors include his wife of three months, Patricia M. Burchett of Arlington, whom he had known since high school; three stepchildren, Jennifer Bent of Chesapeake, Va., John Baker of Warrenton and Russell Baker of Centreville; and six grandchildren.

— Bart Barnes