Karol Kot was born on December 18, 1946, in Kraków, Poland. He grew up in a family that included his father, an engineer, his mother, and a younger sister who was eight years younger than him. The family often traveled to a place called Pcim for their summer holidays. During these trips, a young Kot developed a fascination with butcher shops. He became intrigued by knives, dying animals, and blood. This interest led him to watch death and, with encouragement from some butchers, to drink still-warm pig's blood.

As a child, Kot also engaged in cruel behavior, such as torturing small animals and being abusive to his sister’s cats. He started collecting knives and spent time studying anatomy books. He imagined how he could inflict wounds on people. In school, Kot did well academically, but he lacked social connections and was seen as somewhat strange by his classmates. He was a member of a shooting club and dreamed of becoming a commando or attending an Officer Candidate School.

When he was in college, Kot faced challenges due to a nervous breakdown after failing one of his subjects. Despite this setback, he was allowed to transfer to another technical college focused on communications, where he eventually passed his school-leaving examinations.

Karol Kot's crimes took place over two main periods. The first series began on September 21, 1964. On that day, he attacked Helene Velgen, 48, stabbing her in the back while she knelt in church. She survived this attack. Two days later, on September 23, he followed Franciszka Lewendowska, 78, as she left a tram. He stabbed her in the back on the stairs to her apartment, but she also survived. Just six days later, on September 29, he targeted Maria Plichta, 86, and fatally stabbed her from behind as she walked near a church. Maria died the next day.

There was a break in Kot's crimes for about seventeen months, but he attacked again on February 13, 1966. This time, he fatally stabbed an 11-year-old boy named Leszek Całek at Kościuszko Mound. The next attack occurred on April 14, 1966, when he assaulted an 8-year-old girl named Małgosia. He attacked her as she went to check her mailbox, inflicting eight stab wounds. Although she survived, Kot later returned to ask about her condition.

During the time between his attacks, Kot also attempted to poison people. He bought arsenic and laced drinks at a bar, hoping someone would consume them. He also tried to poison drinks left in public places, but no one was harmed. After boasting about his crimes to a classmate, Kot was arrested on June 1, 1966.

Following his arrest, a search of his home revealed numerous knives and weapons. During police interviews, he confessed to his crimes and faced charges for two murders, ten attempted murders, and four acts of arson. Numerous psychological evaluations confirmed he was sane. At his trial, which began on May 3, 1967, he pleaded guilty to all charges. The verdict was delivered on July 14, 1967, and Kot was sentenced to death, but his sentence was briefly commuted to life in prison. Ultimately, an appeal reinstated the death sentence, which was carried out on May 16, 1968, by hanging.