A British national who was jailed for attempting to steal a police officer's gun in an effort to shoot Donald Trump at a Las Vegas rally was released from prison and deported to the United Kingdom on Wednesday, authorities said.

Michael Steven Sandford, 21, arrived in London on Thursday after a flight from Seattle, Immigration and Customs Enforcement spokeswoman Virginia Kice told the Associated Press. He was being held at a federal prison near the Seattle-Tacoma International Airport.

He served less than five months of his sentence, but was in U.S. custody for nearly 11 months.

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In December, Sandford was sentenced to a year in prison after he pleaded guilty to being an illegal alien in possession of a firearm and disrupting an official function, the Guardian reported.

"I tried to take a gun from a policeman to shoot someone with, and I'm pleading guilty," Sandford told the judge during his hearing last September.

He was in the U.S. illegally after overstaying his visa by 90 days. A federal judge acknowledged in December that Sandford was diagnosed with psychotic mental illness.

Sanford was arrested on June 18, 2016 after he lunged for an officer's gun inside the Treasure Island hotel-casino during a campaign rally for Trump, who was the U.S. Republican presidential candidate at the time. He asked the officer if he could get an autograph from Trump, court documents showed.

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He later admitted to police he traveled from California to Las Vegas with the intention of assassinating Trump, according to court documents. He rented a 9 mm pistol and practiced firing it at a gun range the day before the incident.

Sandford could have faced up to 20 years in a U.S. prison if he was convicted.

The plea agreement, though, called for 18 to 27 months in prison for the offenses. It also said "it is almost certain that [Sandford] will be permanently removed" from the U.S.

The Associated Press contributed to this report.