Ryan Routh charged with attempted assassination of Trump

US prosecutors have charged a man arrested near Donald Trump's Florida golf course with the attempted assassination of a presidential candidate.

It comes a day after a court filing showed Ryan Wesley Routh had written a note months ago saying he intended to kill Trump.

Routh, 58, already faces up to 20 years behind bars on two gun-related charges.

But he faces a maximum sentence of life in prison if convicted on the new, more serious charge.

“Violence targeting public officials endangers everything our country stands for," US Attorney General Merrick Garland said in a statement, vowing to "use every available tool" to hold Routh accountable.

Trump has accused the government of mishandling the case, writing in a social media post on Monday that the justice department should “LET FLORIDA HANDLE THE CASE!”

But Garland rebuffed that, telling reporters on Tuesday that his agency will “seek to cooperate and get assistance from” state officials “consistent with the law”.

Court documents show the case has been assigned through random selection to US District Judge Aileen Cannon.

Ms Cannon is the South Florida judge who was assigned last year to Trump's federal classified documents case and who threw it out earlier this year. Her decision is currently under appeal.

A separate judge on Monday ordered Routh to remain in custody after prosecutors argued he was a flight risk and a danger to the community.

The suspect is being held at a detention centre in South Florida since his arrest on 15 September.

Earlier that day, a Secret Service agent had spotted his rifle poking through a fence at Trump International Golf Club in West Palm Beach.

The agent opened fire as the three-time Republican presidential nominee was playing a round of golf.

Routh fled without firing a shot, leaving his weapon and other items at the scene as agents escorted Trump to safety.

He was arrested shortly afterwards, after a witness spotted him on the highway.

On Monday, new court records unveiled evidence to suggest Routh had been plotting his attack on Trump for months.

In a pre-written letter addressed to "The World" and sent to an unnamed witness months earlier, Routh appears to pre-empt a failed assassination attempt on the former president.

"I tried my best and gave it all the gumption I could muster," the letter reads, with the offer of a cash reward to anyone "who can complete the job".

In addition to the attempted assassination charge, an eight-page indictment unsealed on Tuesday also charges Routh with:

• possessing a firearm in furtherance of a crime of violence;

• possessing a firearm as a felon;

• possessing a firearm with an obliterated serial number;

• assaulting a federal officer

According to the indictment, Routh "did forcibly assault, oppose, impede, intimidate, and interfere" with a Secret Service special agent.

He returns to court for an arraignment hearing on Monday 30 September, where he is expected to enter a plea.

Separately on Tuesday, his son, Oran Routh, was arrested on federal charges of receipt and possession of child pornography.

Authorities discovered "hundreds" of pornographic files while searching the younger Routh's residence in North Carolina over the weekend in connection with the investigation into his father.

Routh's alleged plot was the second attempt on Trump's life after Thomas Matthew Crooks, a 20-year-old armed with an AR-style rifle, opened fire on the former president during a campaign rally in Butler, Pennsylvania in July.

Crooks was shot dead by counter-snipers.