A suspected gunman arrested near Donald Trump’s golf-course wrote a note months earlier saying he intended to kill the former president, a court filing shows.

“This was an assassination attempt on Donald Trump,” the note says.

In court documents filed on Monday, prosecutors said the letter was dropped off at the home of a witness several months before the 15 September incident in Florida.

Ryan Routh, 58, is expected to appear at a federal court later on Monday and could face further charges.

He is so far facing two federal gun crime charges.

The pre-written note appears to pre-empt a failed assassination attempt. “I failed you. I tried my best and gave it all the gumption I could muster,” it reads.

The court documents filed by prosecutors in support of Mr Routh’s continued pre-trial detention noted that a box containing the letter – as well as ammunition, building materials, tools and four phones were dropped off at the home of the unnamed witness before the incident.

Mr Routh has been held in jail since his arrest on 15 September, when police say he was seen with an SKS-style rifle in foliage near Trump’s golf club in West Palm Beach.

The court documents also indicate he had 11 rounds in the incident, one of which was chambered in the rifle.

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