A troubled British teenager who threw a six-year-old French boy from a viewing platform at London's Tate Modern art gallery was on Friday jailed for life.
Judge Maura McGowan told Jonty Bravery, 18, he would spend at least 15 years in custody for attempting to murder the boy in front of horrified crowds on August 4 last year.
But she also said: "You may never be released."
The young victim, who cannot be identified because of his age, was hurled head first off the 10th floor gantry at the gallery and plunged 30 metres (100 feet) on to a fifth-floor roof below.
He broke his spine, legs and arms and suffered a head injury. His condition has since improved but he still requires round-the-clock care and may never fully recover.
McGowan said what Bravery had done was "callous" and "beyond imagination".
She told him he would remain "a grave danger to the public", adding: "You almost killed that six-year-old boy... The injuries you caused are horrific.
"That little boy has suffered permanent and life-changing injuries."
'I am mad'
Bravery has been detained in a high-security psychiatric unit since the attack, which he said he carried out because he had not been given proper treatment for mental health issues.
The burly teenager, who was 17 at the time, was diagnosed with Autism Spectrum Disorder (ASD) at the age of five and has a personality disorder.
Psychiatrists said he also had psychopathic traits, although he had not been formally assessed for the condition.
When challenged about what he had done on the day of the attack, he is said to have smirked and replied: "Yes, I am mad... It's not my fault. It's social services' fault."
British media have questioned how he was able to carry out the attack, since he was living in supported accommodation and under the care of social services.
The court was told he had also indicated he would carry out such an attack, in a secret recording purported to have been made by his carers that was never shared.
McGowan said she had weighed the submissions of medical experts and concluded that he would not get more treatment in a secure unit than in prison.
She reduced the sentence because of his age and his early guilty plea.
But she told him: "I cannot emphasise too clearly that this is not a 15-year sentence. The sentence is detention for life. The minimum term is 15 years.
"Your release cannot be considered before then. You may never be released."
Bravery, who followed proceedings via videolink, showed no emotion as the sentence was passed.
The boy's parents were not in court to hear the sentence but issued a statement via London's Metropolitan Police in which they said Bravery's actions were "unspeakable".
"Words cannot express the horror and fear that his actions have brought upon us and our son who is who is now wondering why he is in hospital," they said.
"How can someone explain to a child that someone deliberately tried to kill him?"
Their son faced "many years" of rehabilitation and physiotherapy. Since January he has been able to eat again but he remained tired, spoke little and was very weak.
Nearly one year on, he is in a wheelchair, has splints on his left arm and both legs, and has trouble sleeping. Family life has been put on hold, they said.
The London council which was responsible for Bravery's care before the attack said it extended its "sincere sympathies" to the French boy and his family.
"A serious case review is under way," a spokesman said in a statement.
"We are cooperating fully and will learn from the findings."
© Agence France-Presse