A man who authorities say staked out Donald Trump for 12 hours on his golf course in Florida and wrote of his desire to kill him was indicted Tuesday on an attempted assassination charge.

Ryan Wesley Routh had been initially charged with two federal firearms offenses. The upgraded charges contained in a five-count indictment reflect the Justice Department's assessment that he methodically plotted to kill the Republican nominee, aiming a rifle through the shrubbery surrounding Trump's West Palm Beach golf course on an afternoon Trump was playing on it. Routh left behind a note in which he described his intention, prosecutors said.

Court records show the case has been assigned to Aileen Cannon, a Trump-appointed federal judge who generated intense scrutiny for her handling of a criminal case charging Trump with illegally hoarding classified documents at his Mar-a-Lago estate in Florida. She dismissed that case in July, a decision now being appealed by special counsel Jack Smith's team.

The attempted assassination indictment had been foreshadowed during a court hearing Monday in which prosecutors successfully argued for the 58-year-old Routh to remain behind bars as a flight risk and a threat to public safety.

They alleged that he had written of his plans to kill Trump in a handwritten note months before his September 15 arrest in which he referred to his actions as a failed "assassination attempt on Donald Trump" and offered $150,000 for anyone who could "finish the job." That note was in a box that Routh had apparently dropped off at the home of an unidentified witness months before his arrest.

The person opened the letter, took a photograph of the front page of the letter, addressed "Dear World," and contacted law enforcement after the attempted assassination.

Prosecutors also said Routh kept in his car a handwritten list of venues in August, September and October at which Trump had appeared or was expected to be present.

The charge of attempted assassination of a major presidential candidate carries a potential life sentence in the event of a conviction.

The potential shooting was thwarted when a member of Trump's Secret Service protective detail spotted a partially obscured man's face and a rifle barrel protruding through the golf course fence line, ahead of where Trump was playing.

The arrest came two months after Trump was shot and wounded in the ear in an assassination attempt during a campaign rally in Pennsylvania. The Secret Service has acknowledged failings leading up to that shooting but has said that security worked as it should have to thwart the potential attack in Florida.

The initial charges Routh faced in a criminal complaint accused him of illegally possessing his gun in spite of multiple felony convictions and with possessing a firearm with an obliterated serial number. It is common for prosecutors to bring preliminary and easily provable charges upon an arrest and then add more serious offenses later as the investigation develops.