From 1941 to 1942, as head of the German Military Administration's staff in Belgrade, Turner played a leading role in the murder of Jews and Roma.

In addition, in 1944, as deputy head of the SS Race and Settlement Main Office, he was instrumental in executing Germanization policy, particularly in the General Government and the Soviet Union.

He then entered the Prussian civil service and worked in the pension offices at Wesel, Mainz, Bad Kreuznach and Trier until 1926, becoming in April of that year a Regierungsrat (Government Councilor).

After the incorporation of the Sudetenland into Germany in October 1938, he served there until December, first as the chief of civil administration, and then as the representative of the District President of Egerland with headquarters in Karlsbad (today, Karlovy Vary).

In April 1941, Turner was made head of the German military administration's staff in Serbia and attained his final promotion to SS-Gruppenführer in September.

On 24 September, the brutal Mačva operation began, which saw entire settlements razed and innocent civilians killed or interned in camps north of the Sava river.

[5] Turner alleged, without evidence, that Roma men were working with the Jews in partisan warfare and were responsible for many atrocities, and several thousands were killed.

[9] In December 1943, Turner was appointed Deputy Chief of the Race and Settlement Main Office at SS headquarters in Berlin, under SS-Obergruppenführer Richard Hildebrandt.

[1] In July 1944, when speaking at the SS-Junker School at Bad Tölz, Turner made derogatory remarks about Reichsleiter Martin Bormann and about the relationship between the Party and the SS.