I can't find my father, Francois Paul Leon Mouchet in the 1930 census. He usually went by Frank Mouchet or F. Paul Mouchet. He was born in Canada (British Columbia) on 14 November 1906. In the 1929 Los Angeles city directory he's listed at 8642 Gregory Way. In the 1930 L.A. city directory he's listed at 1654 Murray Drive. In his citizenship application he also listed 1426 Edgecliff as an address for that time period.
I found the rest of his family in the 1930 census without any trouble and he wasn't with any of them. His twin brother George T Mouchet was living in Washington County Idaho, his sister Suzanne Mineo was in San Diego and his step-father, mother and younger sister were in Clarkston, Washington (Nathan, Marie and Helen Randall).
I never found him in the 1940 census either. He was supposedly living at 715 North Kenmore in L.A. at that time.
All of the above people were born more than 100 years ago, except for Helen Randall. She died in 1996 (see california death index).
I got a copy of his file from U.S. Citizenship and Immigration services and it was a single application with several supporting documents. He was filing for derivative citizenship because, after his father died, his mother married an American citizen. He started the process on 28 April 1944 and received a certificate of derivative citizenship on 4 December 1944.
In answer to bgwiehle's questions:
At one time, I did go through page by page of one of the enumeration districts and didn't find the address. I had worked from a nice web page that converted an address to an ED for Los Angeles. I searched indexes from Ancestry, FamilySearch and Heritage Quest. I had not heard of Mocavo; I'll check them out.
Sometimes he had roomed with his brother. At other times he had a roommate named O.B. Shaffer. I'll see if I can find him.
One address was an apartment building and the other a house. Presumably he was renting a room at the house. I'll try and find a reverse directory for that time period to get the homeowner's name.
His naturalization application stated that he had not left the country since entering it originally.
Thanks, bgwiehle, for your thoughtful suggestions. I now have some more avenues to pursue.