Federal prosecutors charge Ryan Routh with attempted murder of Donald Trump

Federal prosecutors have formally charged Ryan Routh with attempting to assassinate former President Donald Trump.

The indictment adds three additional counts – including attempted assassination of a major presidential candidate, possession of a firearm in furtherance of a violent crime and assault on a federal officer – to the two federal weapons charges Routh already faced.

The move was expected and announced by prosecutors at a court hearing on Monday and by Attorney General Merrick Garland at a press conference on Tuesday afternoon.

“Violence against public officials threatens everything our country stands for, and the Department of Justice will use every tool available to hold Ryan Routh accountable for the attempted murder of former President Trump as charged in the indictment,” Garland said in a statement. “The Department of Justice will not tolerate violence that strikes at the heart of our democracy, and we will find and hold those who perpetrate it accountable. This must stop.”

He is expected to face the charges at a court hearing next week.

Judge Aileen Cannon, the Trump-appointed judge who dismissed Trump’s classified documents case, was randomly assigned to oversee the Ryan Routh case.

Routh, 58, had previously been charged with possession of a firearm as a convicted felon and possession of a firearm with an obliterated serial number in connection with the incident, which occurred on September 15 at Trump International Golf Club.

On Monday, prosecutors released new details of their investigation, saying there was “sufficient evidence to support additional charges that can and should be reviewed by the court.”

Routh had a list of locations between August and October where Trump had appeared or was expected to appear. He is suspected of having been near the golf course and Trump’s Mar-a-Lago resort several times in the month before his arrest, prosecutors said in an arrest motion.

In their memo, prosecutors also revealed that Routh allegedly sent a letter to a civilian witness “several months before” his arrest, saying, “This was an assassination attempt on Donald Trump, but I failed you.”

The government argued that the only reason Routh was in West Palm Beach on September 15 and the following month was “one reason and one reason only, to kill the former President of the United States.”

On the day of the assassination, Trump was playing golf on the course when, according to investigators, a Secret Service agent spotted the barrel of a handgun sticking out of the row of trees near the sixth green.

The agent then fired in the direction of the rifle and saw Routh flee the area and get into his nearby vehicle, according to the criminal complaint filed in the case.

In the treeline area where the suspect was seen, agents found a digital camera, two bags, including a backpack, and a loaded 7.62 x 39 SKS rifle with a telescopic sight, according to the complaint.

Trump was unharmed in the incident and was taken to a safe location by Secret Service agents.

ABC News’ Katherine Faulders and Aaron Katersky contributed to this report.