After American authorities charged him with spying for the East German government in 1983, he became part of a high-profile prisoner exchange between the U.S. and the Soviet Union.
"[5] After purchasing the documents, the East Germans realized they lacked the expertise in Washington to evaluate the intelligence, so they called on Zehe in Mexico City.
[6] He was subsequently charged under the Espionage Act with conspiracy to obtain classified documents related to military technology and deliver them to a foreign government.
[6] The decision to arrest him at the conference with television cameras on hand was designed to fuel public awareness of the dangers of scientific espionage.
[7] The FBI later asked the American Vacuum Society to furnish it with the names of the 2600 attendees at the Boston meeting and threatened to subpoena the information.
[9] Vogel contacted Alan Dershowitz to oversee the legal aspects of the effort and Ronald Greenwald to act as personal liaison between him and Zehe.
[5] Dershowitz, seeking to avoid a conflict of interest with his then-client Anatoly Shcharansky, a founder of the Refusenik movement who had been imprisoned in Moscow for allegedly spying for the United States, brought in Harvey A. Silverglate to defend Zehe.
He also told how at Robert Mueller's direction, prosecutors used "national security" as a reason to withhold documents from the defense even though they were prepared to let the East Germans review them.