Joe had attended Arizona State University in Tempe, Arizona. He was a civilian contractor held prisoner on Wake Island by the Japanese military during WWII. When it was apparent that the island was about to be retaken by the United States, Joe and 97 other civilian contractors were executed by the Japanese.
After the war was over, the Japanese officer who ordered this execution was found guilty of war crimes and was hanged on the island of Guam.
11-year-old Joe Mettendorf appears in the 1930 census for Mayer, Yavapai, AZ living with his 12-year-old sister, Valle Virginia Mettendorf (aka Valle V. Street), his re-married mother, Veola L. Detrick (Viola Isadora Dedrick, b. 1886 in TX) and his stepfather, George C. Detrick (George C. Dedrick, b. 1874 in IA).