Theresa (sometimes spelled Teresa) Fuchs was born in 1860 to Joseph and Mary Fuchs. Later, Theresa's surname was Americanized to Fox. Theresa Fuchs/Fox married Dr. John P. Siegfried about 1888, according to the 1910 U.S. Census for Ashtabula County. Dr. and Mrs. Siegfried had two children, Irene Siegfried, born in Michigan in 1890, and Rudolph Siegfried, born in Ohio in 1899.
Theresa Fuchs/Fox Siegfried passed away in February of 1920 in Ashtabula, Ohio. She was survived by her son and daughter, as well as three sisters: Mrs. Charles Erbe, Miss Kate Fuchs, and Mrs. M. Quinlan, all of New York City. Her obituary, which was carried in the February 10, 1920 Sandusky Register, stated that "Mrs. Siegfried was as former Sandusky girl." Theresa Fox Siegfried was buried next to her husband, Dr. John P. Siegfried, in Sandusky's Oakland Cemetery.