Frank J. Blackwell, a past mayor of Seat Pleasant and a retired National Security Agency research analyst, died June 28 at Washington Adventist Hospital in Takoma Park. He was 85.

The cause was pneumonia, his son Lloyd S. Blackwell said.

From 1980 until 1992, Mr. Blackwell was the mayor of Seat Pleasant, an incorporated community of about 7,000 in Prince George’s County on the edge of Northeast Washington. He had served on the Seat Pleasant Council before his election to the first of three four-year terms as mayor. His years as mayor included work on issues involving pay for town officials and the establishment of a town police department.

Mr. Blackwell retired from the National Security Agency in 1982 after 38 years of federal service.

Frank John Blackwell was born in Washington and graduated from Cardozo High School in 1946. In 1974, he graduated from Morgan State University in Baltimore.

Survivors include his wife of 63 years, Nina Mae Nash Blackwell of Seat Pleasant; two sons, Lloyd S. Blackwell and Larry S. Blackwell, both of Capitol Heights; four grandchildren; and two great-grandchildren.

— Bart Barnes