 On 17 May 1942, Schulze Boysen stood guard on each of the 19 members, travelling over five Berlin neighbourhoods at different times, to paste the stickers over the original exhibition posters.The Harnacks despaired at Schulze-Boysen and decided not to participate in the exploit, believing it to be reckless and unnecessarily dangerous.It was the discovery by the radio counterintelligence organization Funkabwehr of the illegal radio transmissions by Johann Wenzel, and his capture by the Gestapo on 29-30 June 1942 that eventually revealed the Red Orchestra, and led to the arrest of the couple.