The details that have come to light about the action of the gunman who killed 14 people at Charles University in Prague are shocking as in the suicide note he left he confesses to a double murder he committed in the past, as announced by the Czech police.

In the note found at his home, David Kozak confesses that on December 15 killed a man and his daughter in woods near the city, six days before the Charles University attack.

Police said they were on a list of 4,000 suspects in their murders. Kozak also killed his father, bringing the total toll of his victims in 17.

The attack on the university on December 21 is one of the worst mass murders in the history of the Czech Republic.

Kozak, a 24-year-old postgraduate history student at the university, killed himself after being surrounded by armed police.

The suicide note was discovered by the police at the attacker’s home on December 21 – the same day after the attack. It contained a confession that he had killed a father and daughter in the Klanovice forest on the eastern outskirts of the capital a week earlier.

According to Czech media, the victims are a 32-year-old man and a two-month-old girl.

Police, who had included Kozak on a long list of potential suspects they wanted to question, expressed regret that they had not been able to find him sooner.