Thomas A. Clark Jr. was born in 1861 in Calais, Maine to Thomas A. Clark Sr., an English immigrant, and Ann Winn, an Irish immigrant. He had two sisters. Mr. Clark married Jessie May Anderson on January 23, 1897, in Brockton, Massachusetts, and they had one daughter together. He later married Laura Melissa Anderson on July 13, 1900. The couple lived together in Old Town, Maine, and had one daughter. He worked as a harness maker, and later lived in Providence, Rhode Island.
By 1910, Mr. Clark was incarcerated in the Massachusetts State Prison. He died there of leukemia and multiple cerebral hemorrhages on August 31, 1912, at 51.