Seeking Stefan Jokisch

I just got an email from a member of the MAME development team. They’re trying to find Stefan Jokisch to clear up some source code issues. Some of you may remember his as being active in the IF community several years ago. He was the original author of Frotz. I have emailed him using two addresses:, both of which can be found in the Frotz source code. Does anyone here know of any other way to get in contact with him?