After so many attacks, the police were under enormous pressure to find the culprit, and so extended their investigation.
They increased the number of police patrols in Krakow and officers were told to pay specific attention to young men behaving abnormally.
Investigators analysing the attacks discovered similarities between them. It was found that the killer always acted alone, chose victims weaker than himself, and attacked suddenly, inflicting blows to the abdomen and upper back.
In addition they didn’t believe the attacks to be robberies as the perpetrator never spoke with the victims and never took anything from them.

It was known that the attacker was a young man, but still police couldn’t find their suspect. Although the police had a report from a taxi driver who had accurately described Kot, authorities from the communist Polish People's Republic decided that a representative of the so-called “private initiative” could not be a credible witness.

Meanwhile, Kot was enjoying his criminal success.
When the newspapers published a photograph of the young boy he had killed, he was so glad that he ran to his friend Danuta and boasted that it was his work.
He planned to wallpaper his entire room with photographs of his young victim.
Danuta did not believe his story, but, after his next attack, Kot again told Danuta everything and she began to suspect that he really was the attacker.
His story was so detailed that she believed that it could not be a product of a sick imagination and so she went to the police.

Kot was arrested on 1 June shortly after he graduated from school.
There is a theory that the police deliberately delayed the arrest until after his final exams. Passing the exams could be used in court to prove the sanity and mental level of the accused. Officers who arrived at Kot’s apartment were astonished when they were met by a sympathetic, kind and polite boy.
Initially, Kot denied everything, but when confronted with his suspected victims, he confessed to everything and proudly began to talk about his achievements.
To one of his surviving victims who recognized him, he said:
“Your memory is good, come here so I can finish you off”
Kot gave a very detailed testimony of his crimes and of his plans that he had not yet managed to carry out.
The plans that he revealed were so extreme that the court had them witheld.
Kot did not display any sign of contrition or remorse.