In May 1945 he joined the quasi-military police service which the Soviets were setting up within their zone in what remained of Germany. By 1952 the entire area had been changed into a separate state, the German Democratic Republic, and Mahler had occupied a succession of senior positions within the police service in the Mecklenburg district. Additionally, in 1946 he joined the new country's newly formed ruling &lt;a href="Socialist%20Unity%20Party%20of%20Germany"&gt;Socialist Unity Party (SED / "Sozialistische Einheitspartei Deutschlands")&lt;/a&gt;. In 1949 he underwent a period of training at the Berlin Police Academy, and from 1950 till 1953 he served as the Police Chief both in Mecklenburg and for the adjacent Schwerin district, while holding the rank of Police Inspector/Colonel. In June 1953 serious public unrest triggered a heightened level of nervousness on the part of the national leadership, and in November 1953 Christian Mahler was relieved of his police functions, after it had been determined that he had had contacts with the west ("Westkontakten"). The contacts in question seem to have involved his long-term partner, a Jewish survivor of the regime in the Ravensbrück concentration camp, whose parents lived in Hamburg. By this time the frontier down the middle of Germany, which in 1945 had simply divided the land controlled by the Soviets from that under US or British administration, had assumed a degree of permanence which had not been universally anticipated back in 1945: Hamburg was on the "wrong" side of it from the perspective of the German Democratic Republic.