Sixteen-year-old Hannah Leflar was murdered in cold blood by a teenaged boy, who had been stalking her for months, a Regina court heard during the second day of his sentencing hearing Tuesday.

In an agreed statement of facts filed by the Crown and defence, the 16-year-old boy admits to recruiting other teens to help him spy on Leflar four months before she was murdered.

But when Leflar got a boyfriend, the group hatched a plot to ambush the two of them at a secluded site behind a north-end elementary school.

Court heard the plan was for one friend to lure the boyfriend and the victim to a spot designated by the group as the “attack zone.” The young person began gathering items that the group would use, including knives and baseball bats.

But the plan was called off when Leflar unexpectedly broke up with her boyfriend.

On the day Leflar was killed in January 2015, the boy convicted of murdering her used an anonymous Facebook account to surreptitiously view the victim’s Facebook profile. He found photos of Leflar and a new boyfriend.

A few hours later, the boy was hiding outside Leflar's house, armed with a hunting knife, waiting for her to come home from school. When she arrived, he followed her inside and stabbed her to death.

Psychologist Elizabeth McGrath testified Tuesday that the teen was “obsessed” with Leflar, saying he had become depressed from not being with her, and committed murder to “self-medicate.”

McGrath said the boy likely suffers from some sort of mood disorder but, over the past two years, has refused treatment. She said the teen regrets what he did.

"Hannah did not deserve to die. She was a good girl,” the teen is quoted as saying in the psychologist’s report.

“I think what I did was wrong. I regret it."

The Crown is seeking an adult sentence for the boy, who pleaded guilty to first-degree murder earlier this year.

A second teenaged boy, who pleaded guilty to second-degree murder, is expected to be sentenced in September. He originally faced a charge of first-degree murder.

The sentencing hearing is scheduled to continue Wednesday.