It is rare that I cite Wikipedia for my research, given its notoriously variable quality, but in this case it is only because English sources on this event are in very short supply. The following summary was one of the few that I found. Quoting Stuart Jeffries’s Grand Hotel Abyss: The Lives of the Frankfurt School, pages 68–69:
Franz Roeckle had started his career by building a rather beautiful Egyptian–Assyrian style synagogue in Frankfurt in 1908, but by 1933 he was a National Socialist party member who was jailed for his part in a pogrom, known as the Rotter Affair, in his native Liechtenstein.
In 1933 Fritz and Alfred Rotter, two well-known Jewish theatre entrepreneurs in Berlin, had fled Germany to Liechtenstein in part to avoid a bankruptcy scandal which had led to them being castigated in the Hitlerite press, but mostly to escape the [Fascists] — propaganda minister Josef Goebbels was seeking to eliminate what he called Berlin’s ‘Jew-ridden amusement business.’
In Liechtenstein, four [Fascists] including Roeckle tried to kidnap the Rotter brothers in order to take them back to Berlin where, most likely, they would have been jailed if not murdered. The brothers managed to flee their hotel, but in the resulting car chase Alfred Rotter and his wife Gertrude plunged from a cliff to their deaths, while Fritz and his companion were seriously injured.
It is not clear whether Alfred and Gertrude’s deaths were accidental or if they were driven off the road by Roeckle and his associates. The four [Fascists] served only short jail sentences for their involvement in the deaths: indeed, Roeckle and the others were freed early after a 700-signature petition secured their parole (the tiny German-speaking Alpine principality included many enthusiastic [Fascist] supporters).
‘It was a political assassination, perhaps not the only, but the most serious of the small country’, wrote the Liechtensteiner historians Norbert Haas and Hansjörg Quaderer later.⁴ If so, the Frankfurt School’s architect was an anti-Semitic murderer. As the Frankfurter Allgemeine Zeitung put it: ‘First he built for Jews, then he drove Jews to their deaths.’⁵