There is a note that ‘Franz’ committed suicide - this may explain the death ‘young’ in 1912.

According to the Ellis Island Shipping records, Franz, age 24, arrived in 1910, to visit a friend Dr. F. Grumbacher and stayed at the Astor.  His next of kin at home was listed as father, Stadtrat [Town Councellor] Cassirer of Charlottenberg, Augsburgerstr. 54. The next year, Friedrich Wilhelm Cassirer, age 23, who gave his next of kin as I. M. Cassirer (Isidor) also of 54 Augsburgerstr, Berlin W 50 arrived also at Ellis Island. Franz was 5’4”, fair, brown hair, gray eyes.663

See also Miscellaneous Album - Max Cassirer Entry.