James John "Jack" Crenca, 75, the president and chief executive officer of Comsearch Applied Technology from 1985 to 1993, died Oct. 28 at home in Silver Spring of progressive supranuclear palsy.

Mr. Crenca was born in Rome and grew up in Providence, R.I. During World War II, he served in the merchant marine as a communications officer aboard ships traveling to and from the Soviet Union. He received a Maritime Combat Ribbon for this service.

Fifty years ago, he settled in the Washington area. He graduated from George Washington University, where he also received a master's degree in engineering administration. He did additional study in engineering administration at American University.

Mr. Crenca was a pioneer in the development of TEMPEST technology, a secure communications process which includes encryption.

He taught radio communications at Chamberlain Vocational High School in Washington from 1949 to 1953. From 1954 to 1985, he was a vice president and electrical engineer at Atlantic Research Corp.

He was a member of the Institute of Electronics and Electrical Engineers and a founding member of the Electromagnetic Compatibility Society.

Mr. Crenca was a former chairman of the Montgomery County Landlord Tenant Commission, president of the Takoma-East Silver Spring Citizens Advisory Committee, president of the Sligo Branview Civic Association and a Democratic precinct chairman.

He was a 42-year member of St. Bernadette's Catholic Church in Silver Spring.

Survivors include his wife of 48 years, Rosalie C. Crenca, former president and 12-year member of the Montgomery County Council, of Silver Spring; two children, James Crenca of Silver Spring and Jacqueline Crenca Rast of Denver; two brothers; three sisters; and two grandchildren.