After initial research in particle physics, he turned to artificial intelligence (neural networks, knowledge engineering, hypertext)[1] in the course of his work for Siemens Austria (1987-1992).
After joining the German diplomatic service in 1992, Ziegeler held different positions in Germany, Paraguay, the United States, and Ethiopia.
He was instrumental in the creation of the IFC Infrastructure Crisis Facility[2] and initiated the German Federal Government‘s concept on powers shaping globalization.
He joined the Federation of German Industries in Berlin in 2013 as Special Representative for International Economic Partnerships and Alliances and returned in 2014 to the Federal Foreign Office as Head of International Economic Promotion in Countries and Regions.
In 2016, he was appointed as German Consul General in Jeddah, Saudi Arabia, and (effective 2018) Special Representative for the Organisation of Islamic Cooperation (OIC).