A 19-year-old British man drove from California to Las Vegas to attempt to kill Donald Trump at a rally at the Treasure Island Casino on June 18, the Secret Service says.

Michael Steven Sandford tried to take a gun from a Las Vegas Metropolitan Police Officer to assassinate the Republican candidate, but failed in his attempt, according to court documents filed in the U.S. District of Nevada court.

Sandford told a Secret Service agent he tried to grab the officer’s gun to “shoot and kill Trump.” He told the agent he thought he could fire one or two rounds before he would be killed by law enforcement, according to court documents.

He is accused of committing an act of violence on restricted grounds, according to the criminal complaint filed by the U.S. Attorney’s office.

On July 6, Sandford appeared in court and pleaded not guilty, The Las Vegas Review-Journal reported. He was indicted on June 29.

In September, Sandford agreed to change his plea to guilty. He will be sentenced in December and is likely to be sentenced to less than two years in prison.

Here’s what we know about Sandford so far. This is a breaking story and we will add more information as it comes in.

1. He Had Been Planning the Assassination Attempt for More Than a Year, the Feds Say

Trump's would be assassin according to reports

19 year old Michael Steven Sandford pic.twitter.com/VeZvIZ2Pc1 — Nick (@9Joe9) June 20, 2016

Michael Sandford told authorities he drove from California with intent to harm Trump, said Secret Service Special Agent Joseph Hall wrote in the criminal complaint. He arrived in Las Vegas on June 16 and went to the Battlefield Vegas gun range to learn how to use a gun the day before the rally, the complaint said. He said he fired a 9mm Glock, which was the first time he had shot a gun, according to the complaint. He fired about 20 rounds during the training.

Sandford also told Secret Service Special Agent Jason Swierkowski that he had been planning to kill Trump for a year “but decided to act on this occasion because he finally felt confident about trying it,” court documents state. He added that he would try it again if he could. In fact, he told the agents reserved a ticket for Trump’s Phoenix rally later the same day.

You can read the full criminal complaint below:

The complaint says Sandford had a U.K. driver’s license. He only moved to the U.S. a year and a half ago and first lived in Hoboken, New Jersey before moving to the Ontario/San Bernardino, California area. He said he drove across the country from Hoboken to California in his 2007 black BMW 328i, but the complaint does not specify how long he was living on the West Coast.

Las Vegas Now reports that Sandford is in the country illegally and overstayed his visa. That status was revealed at his U.S. District Court arraignment.

2. Sandford Told a Police Officer He Wanted Trump’s Autograph & Then Tried to Grab His Gun, Police Say

Sandford struck up a conversation with Las Vegas Metropolitan Police Officer Ameel Jacob, claiming that he wanted to get an autograph from Trump, according to court documents. He then reached towards the officer’s weapon to pull it out of the holster, which was not locked, the Secret Service says. Sandford was then arrested. He was dragged out of the event by police.

Teen arrested at Trump rally in Vegas, intended to grab officer's gun & kill the candidate @jeffpeguescbs has more pic.twitter.com/qlGJ3hU7vk — CBS Evening News (@CBSEveningNews) June 20, 2016

According to court documents, Sandford grabbed the holster and the handle of the firearm with both hands.

Sandford told the Secret Service he thought taking the firearm from an officer would be the easiest way to acquire a gun to shoot Trump, according to court documents. He also said he targeted Jacob because he thought he saw the officer’s holster in an unlocked position.

“The officers assigned to the event were able to quickly take Sandford into custody with little further disruption at the venue,” the Las Vegas Metropolitan Police Department told The Las Vegas Review Journal. “Custody of Sandford has since been handed over to the United States Secret Service, where he will face formal charges.”

3. Sandford Is Facing Up to 10 Years in Prison if He Is Found Guilty

Authorities charged Sandford with trying to commit an act of violence against a person in a restricted area. He could be sentenced to up to 10 years in prison if convicted.

LIVE: Republican presidential candidate @realDonaldTrump at Treasure Island in Las Vegas https://t.co/i4zTnLXmX1 pic.twitter.com/Wuero1f6Vu — Erik Verduzco (@Erik_Verduzco) June 18, 2016

In addition to a statement from Sandford himself, police said that security footage from Treasure Island showed Sandford leave his seat and approach the officer to grab his weapon. Police also spoke with an employee at the Battlefield Vegas gun range to confirm that he went there.

Sandford remains in federal custody after appearing in court for the first time on June 20. During the brief appearance before U.S. Magistrate Judge George Foley Jr., he was appointed a federal public defender, Heather Fraley, and was advised of his rights and the charges.

According to court records, the U.S. Attorney’s office will notify the British consulate of Sandford’s arrest.

His public defender, Fraley, could not be reached for comment. The case is being prosecuted by Assistant U.S. Attorney Jared Grimmer. According to The Daily Beast, his public defender said during the hearing that Sandford is autistic, but can still stand trial.

Sandford’s father, Paul Davey, told The Daily Mail that Sandford’s mother, Lynne, told U.S. authorities about their son, but they could not do anything because he is over 18. Lynne told federal authorities that Sandord was treated for anorexia and obsessive compulsive disorder, the Mail reports.

Davey also told The Portsmouth News that his son wasn’t interested in politics, but was very “upset” for the past three months.

“We thought he was still in New Jersey so obviously when the embassy phoned us up and told us what happened 2,500 kilometres away we didn’t know anything about it,” Davey told The News. “We haven’t been able to speak to him and we’ve had little communication with the authorities.”

Sandford’s father said that he had never been violent and suggested that he might have been talking to someone, but he didn’t want to say he was “radicalized.”

“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 Aspergers, we think somebody has got hold of him and done something,” Davey explained to The News.

Sandford will be back in court on July 5 at 4 p.m. for a preliminary examination.

4. An Ohio College Student Was Arrested After Charging the Stage During a Trump Rally in March

This is hardly the first time a person has been arrested at a Trump rally. Just last week, a man was arrested at his rally in Houston with a gun and was wearing a “Donald Trump” t-shirt.

In March, Thomas Dimassimo was arrested while storming the stage during a Trump rally in Dayton, Ohio.

Trump later accused Dimassimo of being a member of ISIS, which turned out to not be true, according to federal authorities. Dimassimo was arrested and is facing both state and federal charges in Ohio.

Also in March, John McGraw was caught punching a black man at a Trump rally in Fayetteville, North Carolina.

5. Trump Has a ‘Mercenary’ Security Force Along With Secret Service Protection

Although Donald Trump is protected by the Secret Service, Politico reports that Trump has his own “mercenary force” that has employed aggressive tactics to stop protesters during his rallies. These private security officers have been seen wearing street clothes, just keeping an eye out for protesters.

There were around 1,500 people at the Las Vegas rally, according to the Associated Press. Every one of them had to go through metal detectors overseen by the Secret Service and local authorities.

There were also signs posted designating that anyone in the area would be subject to search, which the Secret Service said in court documents made it a “restricted” area under the protection of the agency.