Overview
- Police responded to Cataldi Park after a 911 call about a stabbing and found a 9-year-old child fatally wounded and the child’s father, Mateusz Dzierbun, holding a large kitchen knife.
- Prosecutors say Dzierbun initially told dispatch another person had attacked the child and later admitted he had killed him while making statements that suggested he wanted officers to shoot him.
- Body-worn camera footage reviewed by the District Attorney shows Dzierbun refused orders to drop the knife, stood, raised the blade above his head and ran at officers, who fired and struck him 14 times.
- An autopsy found multiple stab wounds to the child’s neck and torso and detected the antidepressant trazodone in the child’s blood, and Dzierbun’s toxicology showed no alcohol or controlled substances.
- The Santa Clara County District Attorney concluded on July 22–23, 2026 that the officers acted lawfully and will not face criminal charges, closing the criminal-investigative phase while administrative or civil actions were not detailed.