German federal prosecutors say they're launching a study into the influence of former Nazis on the office after the war.

The office said Friday the study will be headed by two German professors, one of law and the other of history, who will investigate how many former Nazis worked for the office and what influence they had. It's expected to take until 2020.

It will examine the postwar period until 1974, when many prosecutors and judges from the Nazi era are known to have continued practicing in the German judiciary.

One subject will be former head prosecutor Wolfgang Fraenkel, who served for three months in 1962 until he was forced into retirement after details came to light of his service during the Third Reich, including dozens of death penalty cases