A 16-year-old boy who stabbed teacher Ann Maguire to death in England in a "monumental act of cowardice and evil" has been warned he may never be released from prison.
The sentencing judge said he found the teen's pride and lack of remorse over his actions "truly grotesque".
Mr Justice Coulson told Will Cornick, who stabbed Mrs Maguire, 61, seven times from behind as she taught a class at Corpus Christi Catholic College in Leeds in April, that he must serve at least 20 years in custody before he is considered for release.
But he warned Cornick, who was 15 when he killed his Spanish teacher, that, having read about him, "it's quite possible that day may never come".
The court heard how the teenager held a deep hatred of Mrs Maguire and had planned her murder, telling many of his friends of his desire to kill her.
After the murder he told experts that he "couldn't give a s***" and added: "Everything I've done is fine and dandy."
Cornick winked at another boy before he launched into a savage assault in front of a terrified class full of pupils.
Mrs Maguire was left with stab wounds as bad as any the paramedic who attended had ever seen, including one wound which went straight through her neck and another that cut her jugular vein.
Despite this, the teacher managed to leave the classroom, pursued by the teenager until a colleague bundled her into a room and held the door shut.
Leeds Crown Court heard how Cornick went back into the classroom, sat down and said "good times" in front of his traumatised classmates.
Teachers and police who detained him said he showed a bizarre calmness which continued as he was assessed by a range of experts.
The court heard he has never shown any remorse and has spoken of his pride in what he has done.
The teenager, who the court heard came from came from a loving and supportive family, had also talked of attacking other school staff, including a pregnant woman "so as to kill her unborn child".
Outlining the case in a packed courtroom, prosecutor Paul Greaney QC said Cornick was in Mrs Maguire's Spanish class and his academic reports "had generally been positive".
He said there was nothing to indicate to the boy's parents or teachers a risk of "homicidal violence".
But, he said, pupils noticed disturbing aspects to his personality.
Cornick told other children that he hated Mrs Maguire and wanted her dead.
The prosecutor said: "Late on the night of Christmas Eve 2013 and into the early hours of Christmas Day, 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."
