At the library on Wednesday, we went methodically through the California Death Records - at http://www.vitalsearch-ca.com/gen/ca/_vitals/cadeathm.htm. There are three databases there - for 1905 to 1929, 1930 to 1939, and 1940-2000. The first two are images of alphabetical lists and are not searchable, except by surname. The 1940 to 2000 database is searchable. Unfortunately, we did not find a likely John Robinson Hall (or John R., or J. Robinson, etc.) in the listings. Perhaps he left California?
Then we methodically searched www.Ancestry.com looking for "John Robinson Hall" or "J. Robinson Hall" or "Robinson Hall." There were some entries in the census records, newspaper records and vital records, but they were not the correct person.
However, there was an entry in the "World War II Draft Registrations" for a John Robinson Hall residing in Philadelphia PA in 1942. The image is below: