Zech was born in Swinemünde (today, Świnoujście) and after graduating from the realgymnasium there, joined Infantry Regiment 62 (3rd Upper Silesian) of the Imperial German Army in 1910.

[2] Commissioned an SS-Sturmführer on 31 March 1931, Zech led units of the 25th SS-Standarte, headquartered in Essen, rapidly rising through the ranks to command a company, a battalion and, finally the entire Standarte from 24 August 1931 to 13 July 1932.

After the Nazi seizure of power, Zech was also named Police President in Essen, serving from 14 July 1933 to 1 October 1937 when he was succeeded by Fritz Schlessmann.

From April 1932 to its abolition in 1933, Zech sat as a Nazi Party member of the Landtag of Prussia and, on 12 November 1933, he was elected to the Reichstag from electoral constituency 23 (Düsseldorf-West).

[5] Zech's tenure as SSPF in Krakau coincided with the first phase of the Holocaust in which the occupying Germans undertook actions to isolate, exploit and persecute the Jews of the city.

[8] He also was given the posts of Commercial Director and Deputy Operations Manager at the Altenburg plant of the HASAG armaments company, which was one of the largest arms producers and users of forced labor in Germany.