Klaus Gosmann was born on September 1, 1940, in Germany. He had a troubled youth and began showing signs of deviant behavior early on. Despite this, he managed to pursue higher education and studied economics. However, he did not complete his studies and turned to a life of crime in the early 1960s. Gosmann lived a double life, appearing as an average citizen while planning armed robberies and killings. He struggled with personal failures and financial stress, which may have contributed to his descent into violence. As he began committing crimes, he operated mostly during midday hours, leading to his nickname "The Midday Murderer."

Between 1962 and 1963, Klaus Gosmann carried out a series of armed robberies across Bavaria, Germany, killing seven people in cold blood. His crimes were calculated and often took place around noon, a time when many wouldn’t expect violent attacks. His victims were typically people working at banks or businesses, and he showed little hesitation in using deadly force to get what he wanted. The precision and timing of his attacks made him notoriously hard to catch.

Gosmann was arrested in 1963 and brought to trial in 1967, where he was convicted of seven counts of murder. He was sentenced to life in prison, which in Germany typically allows for parole consideration after 15 years. However, due to the severity of his crimes, Gosmann remained imprisoned for 50 years, becoming Bavaria’s longest-serving inmate.

In 2015, at the age of 74, Klaus Gosmann was released from prison under strict conditions. His release stirred controversy in Germany due to the brutal nature of his crimes and the belief by many that someone who killed so mercilessly should never walk free.