Father shot and killed by Police After Stabbing Son in San José

On July 13, 2025, at approximately 3:23 PM, San José Police Department officers responded to a 911 call reporting a stabbing at Cataldi Park in San José’s Berryessa neighborhood. The caller, 48-year-old Mateusz Dzierbun of Fremont, claimed an unknown person had stabbed his 9-year-old son. Upon arrival, officers found Dzierbun, armed with a large kitchen knife, hunched over his bleeding son. Despite attempts to de-escalate, Dzierbun refused commands, stood abruptly, raised the knife, and charged at the officers, prompting two officers—one with 4.5 years and another with over 19 years of experience—to shoot and kill him.

Officers then discovered the boy, Dzierbun’s son, had succumbed to multiple stab wounds. Police determined Dzierbun was the killer, having orchestrated a “s*****de by cop” by luring officers to the scene after murdering his child. The boy’s facial injuries were described as horrific, leaving a lasting impact on responding officers. San José Police Chief Paul Joseph, a 33-year veteran, called the incident one of the most disturbing he had encountered, labeling it a “twisted plan” and an “unfathomable act of violence.”

Dzierbun had no known criminal or mental health history in Santa Clara or Alameda counties. Detectives are investigating his motives and why he chose Cataldi Park, a quiet community space with pickleball courts and picnic areas. The incident, the city’s 13th homicide of 2025, left the community in shock. Mayor Matt Mahan expressed heartbreak, noting the child’s fear when his protector became his attacker. A witness, James Testa, described the emotional toll of seeing the tragedy unfold, highlighting the trauma felt by all involved.