I'm back now, my parents-in-law relocated and we were there for a week for some final works in the new dwelling.
The Mayor of Siegburg in 1995 was Rolf Krieger, I knew him then because the City of Siegburg is also a member of the DLRG there.
I have also heard that Otto Carius was in Siegburg, but already on 8th March 1945. He is 90 years old now and still working as pharmacist: http://www.tiger-apotheke.de/index.php?option=com_content&task=view&id=35&Itemid=56, in the Tiger's Drugstore!
The Michaelsberg with the Abbey is (or better: was) nearly surrounded by railways. In one text I read something about a blocked road which was passed via a marshalling yard, but I dont find the text at the moment 
Some parts of the railways are taken down now, a crossing-keeper's hut which stood in Siegburg some years ago is still available as model http://www.ebay.de/itm/Posten-Siegburg-1-Agertalbahn-Bausatz-aus-Resin-geeignet-fur-Spur-H0-1-87-NEU-/130672125944?pt=DE_Modellbau_Modelleisenbahnen&hash=item1e6caa67f8 
Christoph