Werner Ferrari was born on December 29, 1946, in Switzerland. As a child, he grew up in various nurseries because his family situation was unstable. This made it difficult for him to form strong connections with others. Due to his introverted nature, he often kept to himself and did not engage much with the other children around him. As he grew older, Ferrari took on different jobs as a laborer.

In 1971, Werner Ferrari committed his first murder in Reinach, Basel-Landschaft. He killed a 10-year-old boy named Daniel Schwan. Ferrari was sentenced to 10 years in prison but was released after serving 8 years.

From May 1980 to August 1989, he abducted eleven children between the ages of 6 and 14 across eight Swiss cantons. Out of these children, eight were murdered, while three remain missing. The missing children are Peter Roth, Sarah Oberson, and Edith Trittenbass. This investigation became the longest-running case in Swiss history, lasting nearly ten years.
 

On August 30, 1989, Werner Ferrari called the police just days after the murder of a girl named Fabienne Imhof. He claimed he had nothing to do with her death. Soon after, he was arrested in his apartment in Olten. During his arrest, he confessed to four murders but denied killing a 12-year-old girl named Ruth Steinmann, whose body was found in May 1980.
 

In 1995, the Baden District Court sentenced Ferrari to life imprisonment for five murders, including the murder of Steinmann. However, in 2002, a journalist named Peter Holenstein uncovered new information that suggested Ferrari might not have killed Steinmann. DNA analysis showed that a pubic hair found on her body did not match Ferrari's.
 

Due to this new evidence, the Supreme Court in Aargau overturned Ferrari's conviction in 2004 for the murder of Steinmann. This led to the investigation of another suspect who had died by suicide in March 1983. A dental report also showed bite marks on Steinmann's body that did not match Ferrari's but instead matched the other suspect.

On April 10, 2007, the Baden District Court acquitted Werner Ferrari of Ruth Steinmann's murder. However, he remained in prison for the other four murders he had confessed to.