Good Samaritan likely saved mother and boy stabbed 26 times by stranger, judge told

When a man randomly ran up behind a Calgary mother, grabbed her six-year-old son and began stabbing him, the woman threw herself at the attacker, shielding the boy with her body, a Calgary judge has heard. 

The child likely survived because of his mother's instincts. The mother likely survived because of a neighbour who ran toward the violent attack instead of away from it.

The stabbing was so vicious, the knife broke in two. 

John Yag, 23, is on trial before Court of Queen's Bench Justice Robert Hall. He has admitted to the near-fatal attack but defence lawyer Andrea Urquhart will argue her client was suffering psychosis at the time and couldn't understand his actions were morally wrong.

If the judge agrees with the defence, Yag would be found not criminally responsible (NCR) and sent to a secure psychiatric facility for treatment instead of prison.

A publication ban protects the identities of the mother and her son. 

Details of the disturbing attack come from an agreed statement of facts presented at trial.

Yag first attacks child

On Oct. 6, 2017, the mother and son were headed to Beacham Park in northwest Calgary after dinner just before 7 p.m. They took a green space cut-through to the park behind several homes. 

Suddenly, they heard rapid footsteps approaching from behind. 

It was Yag. He grabbed the boy and stabbed him in the neck. 

The mother launched at Yag. Her son was now on the ground on his back and she covered him with her body.  

Yag's attack continued as he repeatedly stabbed both victims.

Neighbours heard screaming and called 911.

Good Samaritan stops attack 

Some came out of their homes and witnessed Yag hovering over the mother "forcefully swinging at her in a stabbing motion."

One neighbour's backyard runs alongside the cut-through to the park where the two were being attacked. CBC News has agreed not to name the neighbours to protect their privacy. 

The neighbour ran from his home when he heard the screaming and yelled at Yag, causing him to stop. Yag began walking away from the victims.

At that point, the witness got a better look at what had been taking place. 

There was a mother lying on top of a child. Neither one was moving.

'It's just a little boy'

The neighbour's wife also came out of the family home, holding their toddler. 

Fearing for everyone's safety, the witness yelled for his wife and neighbours to get inside

As his wife was calling 911, he yelled at her: "It's just a little boy, he's stabbed."

The neighbour then ran to the pair and saw the extent of their injuries. He stayed with them and tried to reassure them that help was on the way.

He kept the two talking to keep both conscious.

First responders arrived and took both victims to hospital in life-threatening condition. 

Mother waits hours to learn son survived

The boy was taken to the Alberta Children's Hospital while his mother was taken to Foothills. 

It was hours before she was updated on her son's condition. Once at hospital, the boy was taken in for emergency surgery.

Back at the crime scene, as police searched for Yag, he returned to the area. He was covered in blood. 

The neighbour's wife told officers that after he walked away from his victims, Yag looked spaced out and almost lost.

The mother was stabbed 17 times and the boy suffered nine stab wounds. Both victims required surgery.

"The major constellation of wounds are to [the mother's] back as she had thrown her body over [her son] to protect him," reads the agreed statement of facts.

Although it was believed he might not recover full use of his right arm, the boy regained most of its functioning through physical therapy and drumming.