a) The name "Fritz" is a diminutive of the German name "Friedrich," which means "peaceful ruler." It has been used since the 1880s and is also associated with German and Ashkenazi jewish culture.

b) Josef Fritzl changed his name to Josef Mayrhoff...

"The Mayerhof surname is also used as a jewish name, and is more frequently found among the Ashkenazi jewish community of Central and Eastern Europe. Spelling variations of the name include Maierhof, Mayerhoff, and Mayerhoffs."