LONDON — The parents of a young British man who allegedly tried to shoot Donald Trump say they had contacted the U.S. authorities asking for help to bring their vulnerable boy home before he was arrested at a campaign rally in Las Vegas.

Michael Steven Sandford, 20, appeared in court in leg irons on Monday. He faces up to 10 years in prison after allegedly confessing to a Secret Service agent that he had plotted to assassinate the presumptive Republican nominee.

He was arrested after making a grab for a cop’s weapon at a campaign rally at the Treasure Island casino in Las Vegas on Saturday. He allegedly approached the police officer and asked about obtaining an autograph from Trump before reaching out with both hands and trying to pull the gun from the officer’s holster.

The Secret Service agent who questioned Sandford said he confessed that he drove to Vegas from Hoboken, New Jersey, where he was living in his black BMW, with the clear intention of killing Trump. Sandford arrived in Vegas on June 16 and went to a shooting range the following day for his first ever lesson on firing a gun.

According to the agent, after firing 20 rounds from a 9mm Glock pistol, Sandford decided he was ready to make his assassination attempt the following day.

When asked why he tried to grab the gun on Saturday, Sandford allegedly told the Secret Service agent: “To shoot and kill Trump.”

The agent also alleges that Sandford said he would try again to kill Trump if he were released from custody. He also had a ticket to Trump’s next rally in Phoenix. On Friday, a man carrying a gun was arrested at another Trump rally, in Texas.

Sandford, who grew up in the suburbs of Surrey, close to London, reportedly said he had been in the U.S. for 18 months after overstaying his visa.

His parents were begging him to come home, and grew increasingly concerned over the last three months. His father told local Portsmouth paper The News that he had recently become "upset" but they didn't know why because his Asperger's syndrome made it very hard to express his emotions.

“He's been refusing to come back and we were worried about him, we were in contact with the American Embassy telling them we were worried about him. The American authorities said, 'He's over 18 we can't do anything,’” said Michael Davey, who split from Sandford’s mother when the boy was four.

A public defender said while Sandford is autistic, he is competent to stand trial. The court heard that he suffered from obsessive-compulsive disorder and anorexia as well as Asperger’s; he escaped from a hospital in England where he was being treated at the age of 14.

Sandford had fallen in love with an American girl when he was 18 but she moved back home to New Jersey with her parents, according to Davey.

He became so depressed that his parents gave him the money to travel to the U.S. to live closer to his girlfriend. Davey said he didn’t know if the couple were still together as his son rarely shared details of his private life.

“Since he moved out there it became slowly harder and harder to get in touch with him. He does Skype, but it’s always with a white background behind him so you don’t know where he is,” Davey told The News.

“He’s never been very good at communicating, he’s never been interested in politics and never really been interested in much… Because of his condition, he never talks about his private life and it’s always had quite an impact on how he behaves. He left school when he was 15 because he couldn’t cope with it all so he’s got no qualifications or job experience.”

Davey said his son was never a loner, he did have friends at school, although he was often shy when meeting new people.

“I don’t want to use the term radicalized but we don’t know who he has been speaking with—this just isn’t him,” he said. “It’s an absolute shock, he’s never been violent in the slightest, he’s always been a polite and peaceful boy.”

Sandford’s stunned parents received a call from the authorities on Sunday afternoon. Davey is planning to fly out to see him as soon as possible.

“Whether he’s been blackmailed or put up to it, that’s the only thing me and his mum can think of. It’s so against his nature and obviously with his Asperger’s, we think somebody has got hold of him and done something,” he said.

“He has no interest in politics, the world, geography or anything. He’s not a typical teenager because he doesn’t drink or smoke or do drugs, he’s never had any interest in that.”