W. B. Schwartz also received quite a few letters from family during his time at Leavenworth. The letters were mostly from his daughters, sisters and brothers.
Source:
Letters Received, William B. Schwartz, Prisoner no. 5476; Inmate Case Files, U. S. Penitentiary, Leavenworth, Kansas, 1895-1931, Record Group 129; National Archives at Kansas City, Missouri.