S.M., whose identity cannot be revealed under the Youth Criminal Justice Act, was 16 when Mark, 29, was gunned down in late 2009.
S.M. was convicted of first-degree murder on June 1. He served as a lookout for Lamar Skeete, 21, who was convicted of Mark's murder in March and sentenced to life in prison in April. S.M. also drove Skeete to and from the scene on Dundas Street West near Runnymede Road where Mark was shot.
S.M.'s 10-year sentence is the maximum under the Youth Criminal Justice Act. He has been credited with two years served because of time spent in pre-trial custody. He will spend another four years under community supervision, meaning he will spend four years in custody.
Judge says youth sentence only chance at rehabilitation
Justice Ian Nordheimer called the slaying "serious and disturbing," but he said S.M. played a limited role in it. Skeete planned the killing and carried it out, the judge said, not S.M.
Nordheimer also said S.M. is willing to rehabilitate and a youth sentence is his only chance to do so.
S.M. smiled to family members after the sentence was delivered in court.
Maureen Mark, Kenneth's mother, wept. She had hoped he would he would be sentenced as an adult.
"It's one of the greatest disappointments I've ever had in my life."
The Crown has said Mark, who was known in his west-end community for chasing away gang members trying to recruit youth, was targeted because he broke a so-called code of silence.
Mark was on his way to work at about 9:45 p.m. one night in late December 29, 2009, when he stopped into a pizza parlour on Dundas Street West. He left the pizzeria to head to the Wal-Mart outlet where he was a night manager, and put on headphones to listen to music while he walked, police have said.
He was shot execution-style in the back of the head.