John J. Costello, 97, of North Andover, died Jan. 16 at Sutton Hill Nursing Home.
Costello served as the dean of Democratic officeholders in Essex County for many years before retiring in 1978. He graduated from Johnson High School in 1933 and received a bachelor's degree from Harvard College and a master’s degree from Boston College. He joined the Boston Municipal Research Bureau in 1942.
He was a member of the North Andover Planning Board and the North Andover School Committee.
Funeral services were Saturday at St. Michael Parish.