No one saw it coming as Cornick was always described as quiet and he usually kept to himself. He was, in fact, considered to be just a normal teenager until the day in April this year when he mercilessly killed his teacher, Mrs Maguire, in front of his fellow students at Corpus Christi Catholic College.
After stabbing his victim seven times at the back and neck, Cornick is said to have just sat down and said, "good times".
According to the judge who ordered Cornick to serve a minimum of 20 years in prison, adding that he might not be released, the latter actually showed a "chilling lack of remorse".
The Leeds Crown Court heard that Cornick told other pupils that he hated Mrs. Maguire according to the BBC.
Cornick was only 15 when he killed Mrs Maguire but was only recently named after Justice Coulson lifted an order that banned his identification.
The teenager stood in the dock and was flanked by two prison officers as his sentence was being read by a clerk. Cornick was reported to be looking straight ahead, showing no emotion as he admitted to murdering Mrs Maguire.
According to the BBC, Prosecutor Paul Greaney QC told the court that the boy had "psychopathic tendencies" and had derived pleasure from the public nature of the killing, something that the judge referred to as "truly grotesque".
It was reported that Cornick has disturbing aspects to his personality.
Cornick told the other children that he hated Mrs Maguire and wanted her dead, he even wrote on Facebook that Maguire, "deserves more than death, more than pain, and more than anything that we can understand".
According to the prosecutor it was late on the night of Christmas Eve in 2013 and into the early hours of Christmas Day that the defendant exchanged messages with a friend on Facebook. "In those messages he spoke of 'brutally killing' Mrs Maguire and spending the rest of his life in jail so as not to have to worry about life or money."
Based on witnesses' accounts, Mrs Maguire had been leaning over her desk to help a girl with her work when Cornick attacked her from behind after winking at another student in the classroom.
The prosecutor said Mrs Maguire ran but Cornick chased her and was stabbing her as she tried to escape.
The victim was stabbed seven times before another teacher came to her aid, alerted by the screams of the children. The witness recalled seeing Cornick's face was emotionless and just walked away. He just went back to the classroom and sat down as if nothing happened, saying, 'that it was a pity she was not dead'.
Mrs Maguire worked at the school for 40 years and was due to retire.
