A teenager who killed a stranger on an Edmonton river valley stairway was given a seven-year sentence Monday — the maximum penalty for second-degree murder under the Youth Criminal Justice Act.

The 16-year-old boy, who cannot be named, pleaded guilty to the charge earlier this year.

Forty-three months of his seven-year sentence will be served in custody. The remaining three years are to be served in the community under conditional supervision.

Youth court Judge Danielle Dalton gave the youth credit for the five months he has spent in prison since he entered his guilty plea.

The 25-year-old victim was found early on May 17, 2010 on the stairs near the Hotel MacDonald in downtown Edmonton. The man, who was last seen alive at an inner-city shelter, died of a single stab wound to the chest.

Investigators stand on the stair landing where a man's body was found early on May 17, 2010. CBCCBC News decided last year not to name him in order to report the details of his troubled past, which included time as a ward of the province.

According to the agreed statement of facts, the youth carried a machete and a knife to the stairway, after earlier indicating on his Facebook page that he wanted to "spill some guts."

He found the victim asleep on the staircase and slashed him across the arm, head and neck. The man died from a knife wound through his heart.

"I'm hurt," the victim's 28-year-old brother said after sentencing. "He took my little brother for no reason."

Teen failed by everyone, judge writes

In her written decision, the judge notes the teen's life was scarred by abuse, substance abuse and violence. He once watched his mother get stabbed during a house party.

"Loss and violence are what this young man has known," the judge states. "Sadly, it is no mystery at all how he has come to be here."

Both the boy's parents struggled with substance abuse and he was taken into government care. He started drinking every day at the age of 11 and soon struggled with drug and alcohol problems of his own.

His mother died in a drowning seven years ago. He lived with relatives and spent time in a number of foster care placements and group homes.

While he needs to face the consequences of what he has done, the youth has been failed by everyone around him, the judge writes.

"First, failed by those who were entrusted with his care, but also by a society at large in which things like this can happen to children. He has had more grief and trauma in his short life than many people have over the course of a lifetime."

The victim, his brother and the convicted teen were all products of abusive childhoods marred by substance abuse. The victim's brother hopes that the boy will turn his life around.

"It would be an honour for my family, from him, to do that," he said.