Johannes Heckmann, a physician (Arzt), and his wife Maria Elisabeth settled in the Volga German colony of Keller on 15 July 1767. They are recorded there on the 1767 census in Household No. 55.
The 1767 census records that Johannes Heckmann came from the German village of Schlechtenwald in the region of Böhmen (Bohemia).
- Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 2 (Göttingen: Göttinger Arbeitskreis, 2001): 353.