<Dunno what made me post this. Please ignore>

Your friend is a poor taxi driver and was the executive director of a GmbH? Who owned the GmbH? What do the owners say?

Your friend should have got a "discharge" from the owner, at the time of termination, confirming that there were no outstanding debts and liabilities.

You took the words out of my mouth Goldtop. Something's rotten in the State of Denmark...

Could be that the real owners projected the "friend" as the nominal owner. So-called "Strohman". Maybe made him sign some documents he never understood?