A teenager inspired by the Columbine High School massacre has been jailed after making bogus bomb threats to hundreds of UK schools and sparking an airport security scare.
George Duke-Cohan twice targeted schools in the UK and US with hoax messages that triggered evacuations, before phoning in a fake report of a hijacked aircraft while under investigation.
The 19-year-old, of Watford, emailed Marlborough College - the Wiltshire school attended by the Duchess of Cambridge - and referred to the Columbine High School shooting.
He was jailed for three years by Judge Richard Foster at Luton Crown Court on Friday.
The Recorder of Luton told him: "You knew exactly what you were doing and why you were doing it, and you knew full well the havoc that would follow.
"You were playing a cat-and-mouse game with the authorities.
"You were playing a game for your own perverted sense of fun in full knowledge of the consequences."
In his sentencing remarks, the judge added: "The scale of what you did was enormous.
"Schools were evacuated and, where they were not, those in charge had to take agonising decisions.
"The passengers and crew on that flight on 9th August must have been terrified when their plane was taken to a quarantined area, and, apart from the financial cost, the onward travelling plans and connecting flights would have been in disarray."
The teenager appeared from custody wearing a grey jumper with a navy collar.
He pleaded guilty to three counts of making hoax bomb threats in September.
Duke-Cohan, who was doing an IT course, first created panic in March 2018 when he emailed thousands of schools in the UK warning about an explosive.
The National Crime Agency said more than 400 schools were evacuated as a result.
Prosecutor Rebecca Austin said he sent emails to more than 1,700 schools in the UK between March 16 and 19 this year.
The emails, sent to a variety of schools including those that cater for children with special educational needs, threatened to set off an explosive device if payment was not made.
They succeeded in causing "alarm and anxiety", and one particular email said: "This is a message to everyone. We've sent in a student with a bomb.
"The bomb is set to go off in three hours' time. If you do not send 5,000 dollars USD to firstname.lastname@example.org. If you do not send the money, we will blow up the device.
"Our site has all the information needed (veltpvp.com).
"If you try to call the cops we will blow up the device on the spot. Any attempt at defusing it yourself will cause it to explode."
Police arrested Duke-Cohan days later, but he was able to send another batch of emails to schools in the US and UK while under investigation in April.
The court heard that Marlborough College was targeted on April 13 by what was referred to as the "Apophis Squad" hoax emails.
Ms Austin said it was "clear" that Duke-Cohan used the influence of the Columbine attack of 1999 to add "authenticity".
The email sent to Marlborough College said: "We follow in the footsteps of our two heroes who died in the Columbine High School shooting."
Duke-Cohan was arrested for a second time and released on pre-charge bail with conditions that he did not use electronic devices.
Before long his name was in the frame for a third hoax, regarding a bogus tip-off that hijackers had taken over a United Airlines flight from Heathrow to San Francisco.
Detectives found that Duke-Cohan had made the calls to San Francisco Airport and its police force while he was on pre-charge bail for the two previous offences.
Speaking to an operator, he identified himself as "Mike Sanchez" and said his daughter had called him in a "distressed state" from the plane.
A tweet sent after the plane landed included the words "9/11 remake".
He was arrested for a third time at his home in Mutchetts Close, Watford, on August 31 this year.
The teenager was sentenced to one year for the emails sent to schools and two years for the airport security scare.
The judge said that, for the purposes of sentencing, he accepted that Duke-Cohan has autism spectrum disorder.
The court heard that Duke-Cohan was responsible for a "denial of service attack" at his own college before the offences he has been jailed for took place.
Judge Foster said: "I of course accept that the age of 18 is not a magical cliff-edge when young people become mature adults, but the fact remains that it is so often those of a similar age to you who develop extraordinary computer skills which, as with you, can then be abused."
The judge said that what Duke-Cohan did was "far removed from anything that could be described as naivety or a cry for help from a sick person".
He also said: "I bear in mind that you are to be sentenced for bomb hoaxes and not for any other offences for computer misuse.
"Nevertheless, your fascination with computer hacking and your motivation of seeking notoriety is indicative of your high culpability."
In his sentencing remarks the judge said Duke-Cohan had "bragged" about his offending and had said how "funny" it was to make hoax calls.
Anya Lewis, mitigating for Duke-Cohan, described him as "vulnerable" and "remorseful".
At one point during the mitigation, a woman wept in the public gallery.
Anne McCracken, from the CPS, said of Duke-Cohan: "His actions and complete lack of regard for other people caused widespread and unnecessary worry."