Willi Kimmritz was born on 26 June 1912 in Germany, the fourteenth child in a working-class family. He received a basic education, completing only up to the seventh grade at a Volksschule. After his confirmation, he began working in agriculture, employed as a farmhand and later as a coachman. His early adult life was unremarkable but eventually marred by criminal behavior.

In 1936, Kimmritz was first convicted of rape and sentenced to three years in prison at Gollnow. Following his release, he married and fathered a child. However, the stability was short-lived. In 1943, he was again convicted, this time for robbing his employer, a wholesaler, and received another three-year sentence. While serving this term, his wife divorced him.

With the end of World War II approaching, the Red Army closed in on German territories. In April 1945, Kimmritz was among the prisoners moved westward from Gollnow. He was eventually released. For a brief period, he worked as a steward for Soviet supply stores, though he was soon accused of embezzlement and fled to avoid consequences. He first sought refuge with his mother in Bad Freienwalde, before relocating to Berlin.

Between 1946 and 1948, Willi Kimmritz embarked on a brutal campaign of violence in the forested regions surrounding Berlin, particularly in the Brandenburg areas to the north and east. He targeted women, luring them into secluded wooded areas where he would rape, rob, and in some cases, murder them. The known victim count rose to four women murdered and at least 45 raped, though he was only formally charged with 13 rapes and 3 murders.

The sheer brutality and randomness of his crimes led to one of the largest post-war manhunts in Germany, known as Aktion Roland. Yet for a long time, Kimmritz remained at large. Survivors helped police draft facial composites that were accurate enough to identify him early, but post-war Berlin was fractured. Jurisdictional complications between Allied occupation zones, limited police manpower, and administrative confusion significantly hindered the investigation. The Berlin Blockade and poor coordination with Soviet authorities made matters worse.

Eventually, on 11 September 1948, a breakthrough occurred. A woman named Else Baethke recognized Kimmritz while dining at a bakery in the Wedding district of Berlin. Baethke had previously seen him with her friend, Frieda Imlau, one of the victims. Kimmritz was arrested shortly thereafter in the French sector of Berlin. During interrogation, he confessed not only to the charges but also admitted to 45 rapes and four murders, along with numerous property crimes.

He was handed over to Soviet authorities and extradited to their sector. His trial began on 18 February 1949 in the district court of Potsdam. Despite his confessions covering dozens of violent crimes, for procedural reasons, he was only prosecuted for 13 rapes and three of the murders. Nevertheless, his admissions and the evidence presented led to a swift conviction.

Kimmritz was sentenced to death on the same day his trial began. His appeal was denied, and the sentence was upheld. On 26 July 1950, Willi Kimmritz was executed by guillotine in the detention center at Frankfurt an der Oder.