Izaak de Hartog - Dwangarbeiter in Opelwerk, Rüsselsheim

Hallo, I am myself searching for Informations about Izaak de Hartog. I found his name on a list from the Adam Opel-Werke in Rüsselsheim (near Frankfurt/Main). He was named there as a dwangarbeider, forced worker. But - as you obviously know - he did not stay there for a long time. It is written, that he was brought to Riga from there, where Opel was leading a "Heereskraftwagenpark" - means a kind of war-factory, where broken lorries were repaired.
I mentioned this in the booklet about forced work at Opel-Faktory during WW2.
In the city of Rüsselsheim some people are active to create remembrance-stones for the exiled or murdered people. Isaak de Hartog, how he was named in the Opel-List, shall be one of the people, who shall be mentioned next time.
Is there any further information about him?
Andrea Neugebauer, (Germany)
andreaneugebauer@gmx.net