He was appointed by Reinhard Heydrich to head department Amt VII, Written Records of the Reich Security Main Office (RSHA).

In 1936, Six earned the high degree of doctor, and became a professor of journalism at the University of Königsberg where he also took up the position of press director for the German Student's Association.

This document, which post-war became known as "The Black Book", was a secret list previously compiled by Walter Schellenberg, Chief of RSHA Amt VI, Ausland-SD, that made up the foreign intelligence branch of the SD.

[1] After Hitler gave up on his attempts to invade Great Britain and Six's planned role never being realized, Six was on 20 June 1941 assigned as chief of Vorkommando Moskau, a unit of Einsatzgruppe B in the Soviet Union.

The report claimed "The Vorkommando Moscow was forced to execute another 46 persons, amongst them 38 intellectual Jews who had tried to create unrest and discontent in the newly established Ghetto of Smolensk."

[8] Unable to link him directly to any atrocities committed by Vorkommando Moskau, the court instead found Six guilty on all counts for forming the organization, then sentenced him to 20 years' imprisonment.

[11] Six was called as one of four witnesses by defense attorney Robert Servatius in the 1961 trial in Israel of Adolf Eichmann, and gave his testimony by deposition in West Germany.

Servatius had wanted to have Six appear in person, but Prosecutor Gideon Hausner stated that the former Nazi general would be subject to arrest as a war criminal.