Joachim Georg Kroll was born on April 17, 1933, in Hindenburg, Upper Silesia, which is now part of Poland. He was the sixth of nine children in his family. His father worked as a miner. During World War II, his father was captured and became a prisoner of war. After the war ended, Kroll's family moved to North Rhine-Westphalia in Germany.

As a child, Kroll faced difficulties. He grew up in a crowded household, which was not easy for a young boy. He did not have a normal childhood. He had tense relationships with his family, especially with his mother. Kroll was shy and felt out of place among his siblings.

In the late 1940s, Kroll's life changed when his family moved. This new environment was different from his early life. He struggled to fit in and often felt lonely. Kroll did not excel in school either, and his academic performance was poor. This lack of success made him feel even more isolated. As he grew older, Kroll took on various jobs, including working as a toilet attendant. Eventually, he moved to Duisburg, where he continued to live and work.

Joachim Georg Kroll began his killing spree in 1955 after the death of his mother. His first known victim was Irmgard Strehl, a 19-year-old young woman who was raped and stabbed to death. Her disemboweled body was discovered in a barn in Lüdinghausen. In 1956, he killed Erika Schuletter, a 12-year-old girl, who was raped and strangled in Kirchhellen, now part of Bottrop.

On June 16, 1959, Kroll murdered Klara Frieda Tesmer, a 24-year-old woman in the meadows of the Rhine near Rheinhausen. Heinrich Ott, a local mechanic, was wrongly arrested for this crime and later hanged himself in jail. The following month, on July 26, he raped and strangled 16-year-old Manuela Knodt in the City Park of Essen. He mutilated her body, cutting slices from her thighs and buttocks.

Kroll continued his assaults into the early 1960s. On April 23, 1962, he raped and strangled 13-year-old Petra Giese in Dinslaken-Bruckhausen. The investigation wrongly led to the conviction of Vinzenz Kuehn. On June 4, 1962, he killed 12-year-old Monika Tafel in Walsum, also mutilating her body, leading to the wrongful arrest of Walter Quicker, who was released but tragically took his own life later that year.

Kroll's crimes persisted, with the abduction of 12-year-old Barbara Bruder in Burscheid on September 3, 1962. Her body was never found. On August 22, 1965, Kroll attacked Hermann Schmitz and his girlfriend Marion Veen. Hermann was killed, but Marion managed to escape.

In 1966, Kroll's victims included 20-year-old Ursula Rohling, who was strangled on September 13 in Foersterbusch Park near Marl. Kroll's next target was 5-year-old Ilona Harke, who was raped and drowned in a ditch in Wuppertal on December 22. In 1969, he killed Maria Hettgen, a 61-year-old woman, also by rape and strangulation.

The year 1970 saw the murder of 13-year-old Jutta Rahn, who was attacked while walking home from a train station. Although Peter Schay was wrongfully arrested and later confessed to the crime, Kroll remained at large. Kroll's final known victim was 10-year-old Karin Toepfer, who was raped and strangled on May 8, 1976. Just two months later, Kroll kidnapped and killed 4-year-old Marion Ketter. This heinous act led to his arrest on July 3, 1976.

During the police investigation, a neighbor reported that Kroll had mentioned "guts" when asked about a blockage in the waste pipe of their building. This prompted the police to search Kroll's apartment. There they found Marion Ketter's dismembered body, with some parts in the refrigerator and others cooking in a pan of boiling water.

Kroll confessed to the murder of Marion Ketter and admitted to killing 13 other people over the previous two decades. He claimed that he cut portions of flesh from his victims to cook and eat, saying it helped him save money on food. He was tried and convicted of eight murders and one attempted murder in April 1982, receiving a life sentence. Kroll died of a heart attack while in prison on July 1, 1991.