Helmut Jahn died of multiple injuries in bicycle crash, autopsy shows By FOX 32 Digital Staff Published German architect Helmut Jahn killed in bike accident outside Chicago Helmut Jahn, a prominent German architect who designed an Illinois state government building and worked on the design of the FBI headquarters in Washington, was killed when two vehicles struck the bicycle he was riding outside Chicago. CHICAGO - An autopsy has determined renowned German architect, Helmut Jahn, died of multiple injuries from a bike accident that occurred last weekend outside Chicago. Jahn, 81, was killed last Saturday while riding his bicycle on a village street in Campton Hills in Kane County, about 55 miles west of Chicago.