Known for his many pseudonyms, his seductiveness, his cynicism and versatility, from Paris to Hollywood from Mexico City to London, he participated in all the major Comintern disinformation campaigns in the 1930s, under the leadership of Willi Münzenberg who he eventually usurped after spying on him for the NKVD, if the rumours were to be believed.

He was strongly suspected, without conclusive evidence, of involvement as Ramon Mercader's handler in the assassination of Leon Trotsky, and in the supposed murder of Willi Münzenberg who was found hanged in a French forest.

Leopold Katz, an uncle of Otto's, was a historian and lawyer famous for having discovered the Jistebnice Hymnal, a collection of Hussite psalms calling for reform.

After classical studies in Prague, where Otto revealed a gift for languages (he fluently spoke five: German, Czech, English, French and Russian), he joined the prestigious Imperial Export Academy, which prepared young men for top jobs in international trade, in 1913 where he became fascinated with the Redl case.

[3] The young Otto's marked preference was for literature, theatre, pretty actresses and all the cultural life of Prague which was very active at that time.

[4] He met a leftist actress Sonya Bogsová, whom he married but their communist activities monitored by the Prague authorities encouraged them to settle in Berlin in 1921.