TEWKSBURY - Thomas James "Mayor" Casey, 74, a decorated Korean War veteran, skilled diver and a longtime Tewksbury resident who had been a town worker and an usher and volunteer at his local parish, died yesterday morning, Dec. 23, at his home after a seven-month battle with cancer. He was the husband of Ruth M. "Chickie" (Bruce) Casey, with whom he celebrated their 53rd wedding anniversary on May 7.He was born in Boston's Charlestown on Aug. 4, 1929, a son of the late Thomas F. and Bridget (Joyce) Casey. He was raised in Charlestown, and later moved to Somerville, where he was graduated from Somerville High School. In 1954, he moved to Tewksbury.Mr. Casey served in the Army during the Korean War. He received many decorations, including two Purple Heart medals for being wounded in combat.Following his military discharge, he was a professional underwater diver and a rigger aboard the U.S.S. Constitution. He later was employed at the Boston Navy Ship Yard, holding a rare certification for Extreme Deep Water Diving. Mr. Casey then began a second career, working for the town of Tewksbury's Water Department. Prior to retiring, he worked for Boutiettes's Auto Body company in Tewksbury.He was an usher and volunteer at St. William's Church, and a charter member of the church's Men's Club. He was a past grand knight and member of the board of directors of the Father. Coppen's Council Knights of Columbus 4336. He was also a member of Bishop Delaney Assembly 4th Degree Knights of Columbus. Mr. Casey was also active in the Disabled American Veterans Post 110, and the Veterans of Foreign Wars Post 8164, both in Tewksbury.He was also active with the Charlestown School Boys, and the Tewksbury Little League "Mets" team. He also served on the Board of Voter Registration in Tewksbury, and had been a Tewksbury safety officer.Besides his wife, he is survived by a son and his wife, Thomas E. and Kathleen (Doherty) Casey of Tewksbury; four daughters and their husbands, Pamela J. and Robert Sullivan of Lowell, Laura A. and Ralph Patterson of Tewksbury, Carol J. and Michael Conwell of North Andover, June L. and Scott Patterson of Tewksbury; a sister, Mary Murphy of Lexington; four brothers and five sisters-in-law, John and Ann Casey of Medford, Michael and Helga Casey, residing in Virginia, Paul and Ann Casey of Westfield, Edward and Carmella Casey of Lexington, and Virgina Bruce of Billerica; 11 grandchildren, Justin and Amy Sullivan, Cristin and Bridget Casey, Megan Brackett, Michael Casey, Troy and Casey Conwell, Callina, Brooke, and Scott Patterson. He also leaves a close friend, Katherine Nickerson of Chicago; and numerous nieces and nephews.He was also brother of the late James Casey, and the brother-in-law of the late Raymond Murphy and Kenneth Bruce.