Richard J. Nadeau, Sr., age 64, died Tuesday, May 4, 2010 at Saints Medical Center in Lowell. He was the beloved husband of the late Rose J. (Beraldi) Nadeau. Born in Cambridge, December 29, 1945, he was the son of the late Thomas and Helen (Coiley) Nadeau. Richard retired in 1993 from the Middlesex County Sheriff's Department, where he had been employed as a correctional officer. He was also available for any special details with the Town of Billerica Police Department. He is survived by his daughter, Jennifer Mallias of Billerica, and his son, Richard J. Nadeau, Jr. of Nashua, NH., his brother, Thomas Nadeau of Bourne, his sister, Helen Stewart of Las Vegas, and his two loving grandchildren, Gina and Nikolas Mallias. He was also the father of the late Gino Nadeau and the brother of the late Paul and Ralph Nadeau.