All available evidence indicates that image is in public domain per research performed by Kenosis:

I researched the history of FBO and RKOs acquisition of it in the late 1920s, and also looked in the US Copyright Office online records to see if there were any renewals in the early fifties. I searched the US copyright records here to see if either RKO or FBO renewed any copyright after 28 years for works that are not motion pictures or musical compositions, e.g., periodicals, collections of photographs, etc. As far as I can tell, there are none under either FBO or RKO. Kenosis 19:28, 30 August 2007 (UTC)