The 9-year-old victim in last week's San Jose stabbing case has been identified and his mother has now put out a statement about the tragic loss of her son, and his father's undiagnosed mental illness.

The horrible case made headlines early last week, with San Jose Police Chief Paul Joseph saying that it was the most disturbing murder case of his 33-year career, and of the officers who responded to the scene, he said, "What they saw yesterday, they will never unsee."

He also said, "I don’t ever remember a parent murdering a child so brutally."

San Jose police say they have evidence that 48-year-old Mateusz Dzierbun of Fremont both murdered his son and pre-planned his own suicide-by-cop, calling 911 to report a stabbing in progress that he had already committed, and luring officers to his location in Cataldi Park. Officers arrived on the scene to find Dzierbun covered in blood and holding a knife over the child's body, and then rushing toward officers with the knife, at which point he was fatally shot by police.

KPIX and others have released a blurry still image of Dzierbun, likely taken from body-worn camera footage, standing and raising the large knife in the air.

The nature of the 9-year-old boy's injuries have not been described. Chief Joseph only said they were "horrific," and witnessing the scene will now be a lifelong burden to the officers who responded.

On Tuesday, for the first time, we heard from the victim's mother, Sandra Rencontre, and she identified the boy as James Konrad Dzierbun. It's not clear whether she had been in recent contact with the boy's father, and police say that Mateusz Dzierbun had "moved around the country" a bit in recent years. But Dzierbun was listed as a resident of Fremont, and the young boy lived in the area, attending Brooktree Elementary School in the Berryessa Union School District, according to an obituary.

As KRON4 reports, Rencontre and other family members say that Dzierbun had an undiagnosed mental illness and "hid his illness well" from the world.

"We wish anyone could have foreseen this situation, but there was no way any of us could have known," Rencontre tells KRON4. "My whole world has shattered in a single moment."

Of her son, James, Rencontre said, "He was so smart: emotionally intelligent beyond his years. He knew how much I loved him, and I’ll never have to regret not telling him that enough."

The mother said she wanted to put out a message about mental health struggles, to warn others to act if a loved one needs help, or to be alert if you yourself "feel a shift in your energy."

"I feel it is important to acknowledge a reality that is too often overlooked and often misunderstood: the role of undiagnosed mental illness," Rencontre said in the statement." While I cannot speak to his father’s state of mind at the time of the incident, I can say that he was once a loving and devoted father. I believe we must confront the reality that mental illness, when left undiagnosed and untreated, can have devastating consequences. While nothing can justify his actions, I wanted to bring an awareness and accountability to everyone."

She added, "This message is not only for those directly affected, but to a society which too often falls short when it comes to recognizing and treating mental illnesses. We all must listen more carefully, respond more urgently, and love more fiercely in order to support or recognize when someone around us is struggling silently."

Rencontre's sister has launched a GoFundMe campaign to assist her grieving sister to cover lost wages and funeral expenses.

"Our hearts are breaking. We could never imagine the loss of this sweet, kind child," the child's aunt writes.