Joseph P. McMahon, 72, who retired from the FBI in 1997 as a section chief specializing in foreign counterintelligence, died April 7 at his home in Alexandria.

The cause was cancer, said a daughter, Elizabeth McMahon.

Mr. McMahon joined the FBI in 1967. In New Orleans, he was supervisor of the political corruption desk. In Memphis, he was assistant special agent in charge of the field office. He settled in the Washington area in 1987 to work in the national security division.

After his FBI retirement, he was a contractor for the CIA-affiliated Center for Security Evaluation until he retired in 2011. A year earlier, the center was absorbed into the federal Office of the National Counterintelligence Executive.

Joseph Paul McMahon, a native of Pittsfield, Mass., was a 1963 graduate of College of the Holy Cross in Worcester, Mass., and a 1967 graduate of Albany Law School in New York.

He was a member of Saint Joseph’s Catholic Church in Alexandria.

Survivors include his wife of 47 years, Maureen Hannigan McMahon of Alexandria; two children, Joseph Joyce-McMahon of Springfield and Elizabeth McMahon of Alexandria; two sisters, Kathleen Collins of Palos Verdes Estates, Calif., and JoAnn Jenkins of Alexandria; and one granddaughter.

— Adam Bernstein