When two police officers confronted Jaswant Singh Chail on the grounds of Windsor Castle on Christmas morning in 2021, he was clad in black, wearing a metal face-mask, and wielding a crossbow. “I am here to kill the queen,” he told them.
On Thursday, Mr. Chail was sentenced to nine years in prison, having been convicted of treason in February. It was the first treason conviction in Britain in more than four decades, in a case that raised troubling questions about the security of Queen Elizabeth II. She died in September 2022 of natural causes, at 96 years old.
Under a so-called “hybrid order,” Mr. Chail, 21, is to remain at Broadmoor Hospital, a high-security psychiatric institution where he is currently being treated, before being transferred to a prison for the remainder of his sentence.
The sentencing judge, Nicholas Hilliard, said in court that a psychiatrist had diagnosed Mr. Chail, who is from Southampton, as “psychotic, delusional, and hallucinating.” After being rejected by the British Army, the judge said, Mr. Chail came to believe he was a “Sith Lord,” a dark character from the “Star Wars” franchise.
“His lifelong interest in ‘Star Wars’ took on different meaning,” Judge Hilliard said.
The judge also read out several text messages that Mr. Chail exchanged with an artificial intelligence chatbot that he created and referred to as his girlfriend “Sarai.” The messages suggested that Mr. Chail was being encouraged by his chatbot to carry out his threat to assassinate the queen.
Mr. Chail bought the crossbow online in 2021 and began searching for information about Sandringham, the country residence where the queen traditionally spent the Christmas holiday. In 2021, however, she and her late husband, Prince Philip, were sequestered at Windsor Castle because of the coronavirus pandemic.
Early on Christmas Day, Mr. Chail scaled the castle’s wall with a nylon rope and spent about two hours roaming the grounds before the Metropolitan Police spotted him at a gate leading to the queen’s private quarters at 8:10 a.m. One of the officers drew a Taser as they approached him, according to a police statement. The officers discovered that he was carrying a crossbow, loaded with a bolt with the safety catch off.
“Morning, can I help, mate?” one of the officers asked Mr. Chail.
“I am here to kill the queen,” he replied, before laying down the weapon and repeating his threat.
Mr. Chail, who is of Sikh descent, told the police he was acting to take revenge for the treatment of South Asians, citing the 1919 massacre in Amritsar, India, during which British troops fired on pro-independence demonstrators.
In addition to treason, Mr. Chail pleaded guilty to two other charges: making threats to kill and possession of an offensive weapon. The case prompted calls on the government to crack down on the purchase of crossbows.
The police said it was an “extremely serious incident,” which the officers defused with “bravery and professionalism.” Dominic Murphy, a senior counterterrorism officer at Met, as the police service is informally known, told the P.A. news agency that Mr. Chail was “dangerous and vengeful.”
It revived memories of an even graver lapse in security in 1982 when an intruder, Michael Fagan, broke into Buckingham Palace, found his way to the queen’s bedroom, and woke her up before she called for help.
A year before that, a man fired six blank shots at the queen as she rode past on horseback during a parade in London. That man, Marcus Sarjeant, was also charged and convicted under the Treason Act.