David Kozák was born on 12 August 1999 in the Czech Republic and grew up in the small town of Hostouň, roughly 21 kilometres west of Prague. He studied at Charles University’s Faculty of Arts, where he earned a bachelor’s degree in History and European Studies before continuing into a master’s program in World History. His academic work earned high marks, his bachelor’s thesis on the Galician Peasant Revolt and the Kraków Uprising of 1846 was graded “excellent” and awarded the Marian Szyjkowski Award by the Polish Institute in Prague.

Kozák had no criminal record, passed enhanced background checks, and was employed at Václav Havel International Airport. Friends and former classmates later described him as academically gifted but socially isolated. Witness statements suggest he struggled to form romantic relationships and that loneliness intensified during his university years, particularly under COVID-19 restrictions. Some acquaintances recalled him speaking of pressure from his parents to finish his degree early, along with strict discipline at home, though his mother denied these accounts and described him as a happy child in a functioning family.

In 2022, a close friend became concerned about his mental state, prompting several psychiatric consultations. While initial sessions focused on suicidal ideation, his thoughts reportedly shifted toward harming others. Despite this, gaps in medical reporting procedures meant his general practitioner was never informed, and a substitute doctor, not his primary physician, later issued the medical clearance required for his gun license.

According to a post-mortem psychological evaluation, Kozák displayed schizoid, narcissistic, and dissociative traits, coupled with a high IQ, but did not meet the criteria for a diagnosable mental disorder. Authorities found no ideological or extremist affiliations, but noted he had an interest in violent media and researched other mass killers.

Kozák’s killing spree unfolded over a single week in December 2023 and became the deadliest mass shooting in Czech history since the country’s independence.

Armed with a Glock 45 fitted with a silencer, Kozák entered the Klánovice Forest on Prague’s eastern outskirts. He initially considered targeting a woman with two children but instead followed a 32-year-old man pushing a stroller down a side path. He shot the man multiple times before killing the victim’s two-month-old daughter. Kozák fled the scene by bus and train, evading police. Investigators initially had no direct leads, narrowing the suspect pool only to firearm owners matching the weapon type.

Six days later, Kozák shot his father three times in the head at their home, then placed his neck on a block of wood alongside an axe, apparently intending decapitation but abandoning the act. His mother contacted police soon after, and a friend alerted authorities that he was armed, dangerous, and suicidal. Police discovered improvised explosive devices in the home, slowing their search.

At 13:23, Kozák entered the Faculty of Arts building at Jan Palach Square carrying multiple firearms, ammunition, and melee weapons. Police had already been searching for him but left the building after an initial sweep, believing he might be at a separate location. At 14:54, he began firing on the fourth floor, killing and injuring students and staff. Victims were shot in classrooms and hallways; some leapt from ledges to escape.

Kozák also moved onto a terrace, firing into the street and injuring bystanders. A police officer armed with a pistol returned fire from over 100 meters away, narrowly missing him. At 15:19, seconds after discarding his rifle, Kozák killed himself with a shotgun.

In total, 17 people were killed, two in Klánovice Forest, his father in Hostouň, and 14 during the university attack. Twenty-five others were injured. The victims at Charles University included twelve students and two staff members, among them the head of the Institute of Musicology and a Germanic Studies lecturer.

Police determined that Kozák had planned the university shooting for months, researching floor plans, class schedules, and nearby public venues. He purchased firearms and ammunition using personal savings and a gift from his grandmother. Official findings stated that his motive was rooted in feelings of social alienation and a desire for notoriety rather than ideological goals.

The attack prompted national mourning, international condolences, and renewed debates over Czech firearms laws and police procedures. Public criticism focused on the police’s failure to prevent the shooting despite having warnings about his danger and proximity. Parliamentary hearings and investigations followed, though internal reviews concluded no officers had committed crimes.

On 20 June 2024, a permanent sandstone memorial was unveiled at Jan Palach Square to honor the victims. The tragedy left a lasting mark on Czech society and remains one of its most scrutinized criminal cases.