In my research for more bibliographic information about Paul Soleillet I have found some additional information about the “drame familial” (family drama) mentioned by Jean Claude Pecker in his bibliography.
This happened in December 1931 when P. Soleillet was 29 years old.
Jean Claude-Pecker, told me he had the opportunity to meet Soleillet (“homme charmant et discret” according to his words) when Soleillet was working with Daniel Chalonge. However he was unable to send me a picture of him (Jean Claude-Pecker is 96 years old) . My search has been completely unsuccessful and, apparently, there are no traces of him at any of the institutions he worked. He remains as a misterious man.