DA clears San Jose officers in deadly shooting of man who fatally stabbed his child

SAN JOSE — Prosecutors have cleared two San Jose police officers of criminal liability for fatally shooting a man who had just stabbed his 9-year-old son to death at a city park last year.

SJPD Sgt. Joel Casey and Officer Eduardo Eyer shot Mateusz Dzierbun, a 48-year-old Fremont resident, 14 times from about 25 feet away after he started to charge at them while holding two butcher knives, one of which he had just used to kill his son James, according to a shooting report released Wednesday by the Santa Clara County District Attorney’s Office.

Twenty-four total shots were fired during the July 13, 2025 afternoon encounter at Cataldi Park, with police bullets hitting Dzierbun in the head, neck and torso, prompting a witness at the park to accuse the officers of carrying out an “assassination style” shooting in his statement to investigators. But the DA’s office concluded that Dzierbun’s remarks to officers, calmly foreboding an attack, and the backdrop of the child-stabbing claim that Dzierbun himself had reported to 911 dispatchers, created a circumstance that justified the officers’ actions.

“The officers were confronted with an extraordinarily dangerous and rapidly evolving situation. The evidence before them indicated only two possibilities: Either Dzierbun had already murdered his son, demonstrating his homicidal intent, or the child had been stabbed by Dzierbun and required immediate lifesaving aid,” the report reads.

The report, signed by District Attorney Jeff Rosen, continues: “By their own accounts, the officers’ primary focus throughout the encounter was reaching the child to determine his condition and render aid if he was still alive. To that end, they repeatedly pleaded with Dzierbun to move away from the child and drop the knife.”

Along with the DA shooting report — which follows every police killing in the county — prosecutors released a one-minute excerpt of police body-camera footage showing officers repeatedly telling Dzierbun to drop the knife he was holding. Instead, he gets up, with the knife raised high with his right hand, and takes about two steps before the officers open fire.

Prior to the shooting, Dzierbun told the officers in reference to stabbing his son, “I had to do it, they were going to torture him,” without explaining the claim. In his 911 call, he reported that another man had stabbed his son, and gave a description of a man that police initially approached before realizing that Dzierbun was the dangerous figure on the scene.

The report also recounted Dzierbun telling the responding officers, “Listen to me very carefully. I am armed, and one of you guys is going to kill me today. I don’t want to traumatize you.” When Casey suggested to another officer to retrieve a less-lethal stun bag launcher, Dzierbun reportedly warned, “If you get the stun bag, I’m going to get up and charge this guy,” referring to a fourth officer at the scene.

After Dzierbun was shot and fell to the ground, officers rushed to the child, whose face was covered with a shirt. When Eyer lifted it, he reported seeing that the the child’s throat had been slashed, and re-covered his face.

A witness told investigators that he was at a nearby pickleball court to teach a group of young boys when he witnessed the shooting unfold. The report states that afterward, he berated officers for the shooting, and that he was detained when he tried to leave. He would later describe the shooting as “assassination-style” to investigators. In remarks the witness later gave to KTVU, he described the situation as a tragedy but did not further criticize the officers.

Casey opened fire after “he heard a scream as Dzierbun came toward him with ‘one knife over the head and another knife in the other hand … It felt like a sprinter getting up and in a sprint,’” according to the report. The report also includes Eyer stating, “I need to save myself and my partners here … I wanted to save that kid.”

The mother of the boy told investigators she was co-parenting him with Dzierbun and received an odd text message from him on the day of the stabbing but did not read it until after the police encounter. The DA report includes her telling of how Dzierbun had joined a new church and was “saying strange things about reincarnation and past lives,” and summoned a “spiritual cleansing woman” to their apartment to deal with an “evil spirit in his room.”

Dzierbun’s death was the second of two fatal shootings involving San Jose police in 2025.