David Kozak said his Telegram channel would be a “diary” of his life “before the shooting”.
To the outside world, he was an introverted loner, but online the Prague University gunman was not shy about sharing his sick fantasies to kill.
David Kozak used online platform Telegram to muse on massacres and mass murder, while also boasting of his plans to carry out a school shooting, according to Czech media.
He said his Telegram channel would be a “diary” of his life “before the shooting”.
“I want to do school shooting and possibly suicide,” the 24-year-old wrote in one chilling post, before adding: “I always wanted to kill. I thought I would become a maniac in the future.”
Kozak went on to praise “Ilznaz”, which is thought to be a reference to Ilznaz Galyaviev, 19, who murdered nine in a 2021 attack on his former school in Kazan, Russia.
“When Ilznaz did the shooting, I realised it was much more profitable to do mass murders than serial ones,” he said.
He also wrote approvingly of Russian school shooter Alina Afanaskina, whom he said “helped me too much”.
The 14-year-old schoolgirl shot dead another student and wounded five others with her father’s pump-action shotgun before turning the weapon on herself in the city of Bryansk this month.
“It was as if she had come to my aid from heaven just in time,” he posted.
The Czech authorities were quick to rule out any links to international terror organisations after the attack.
‘An introverted type’
Kozak, dressed in black and armed with a rifle, certainly seems to fit the profile of a lone gunman.
The student had no criminal record but, as a legal gun owner, he had an interest in weaponry.
He had a bachelor’s degree in history and European studies, and continued with a master’s degree, focusing on the history of Poland.
Kozak would travel the 13 miles from his home to Prague for lectures at Charles University’s Faculty of Arts. It appears he lived in the central Bohemian village of Hostoun with his father in a large family house.
“He was an introverted type, strange, probably like any other nerd,” one resident told local media.
“The family seemed normal. We went to their cottage years ago. His dad used to be mine’s boss and they were friends outside of work, including his wife.”
What exactly happened on the morning of December 21 is not yet clear. What has been established is that Kozak murdered his father before heading to Prague.
Czech police learned that he was heading to the capital and planned to take his own life.
Suicide featured heavily in Kozak’s social media posts, where he poured out his darkest thoughts.
He was due to attend a lecture at 2pm and opened fire just before 3pm.
In the bloodshed that followed, he fulfilled his crazed ambition to become a mass murderer.
As police swarmed towards him, he is said to have turned his weapon on himself and inflicted what was described as a “devastating” injury after a shootout with officers.
It is thought he may have been shot by police first before he killed himself to avoid arrest.
Kozak kept his Telegram channel private until just before his attack, when he made it open to read.
Posts taken from it spread across social media, granting him the notoriety he clearly craved, as news of the Czech Republic’s worst-ever mass shooting emerged.
His chilling “diary” has now been taken down, but not before he had opened a chapter of pain and grief for the friends and families of his many victims.