WEST PALM BEACH, Fla. — The man accused in the assassination attempt of Donald Trump at a golf course in Florida left behind a note detailing his plans to kill the former president and kept in his car a handwritten list of dates and venues where Trump was to appear, the Justice Department said Monday.

Trump complained that the holding charges were too light, but prosecutors indicated attempted assassination charges were coming.

The new allegations about the note were included in a detention memo filed ahead of a hearing Monday at which federal prosecutors argued that Ryan W, Routh should remain locked up as a flight risk and a threat to public safety. U.S. Magistrate Ryon McCabe agreed, saying the “weight of the evidence against the defendant is strong” and ordered him to remain jailed.

The latest details were meant to bolster the Justice Department’s contention that the 58-year-old had engaged in a premeditated plan to kill Trump, a plot officials say was thwarted by a Secret Service agent who spotted a rifle poking out of shrubbery on the West Palm Beach golf course where Trump was playing and then opened fire in Routh’s direction.

The note describing Routh’s plans was placed in a box that he dropped off months earlier at the home of an unidentified person who did not open it until after his arrest, prosecutors said.

The box also contained ammunition, a metal pipe, building materials, tools, phones and various letters. The person who received the box and contacted law enforcement was not identified in the Justice Department’s detention memo.

One note Routh left, addressed “Dear World,” appears to have been premised on the idea that the assassination attempt would be unsuccessful.

“This was an assassination attempt on Donald Trump but I failed you. I tried my best and gave it all the gumption I could muster. It is up to you now to finish the job; and I will offer $150,000 to whomever can complete the job,” the note said, according to prosecutors.

The letter offers “substantial evidence of his intent,” Assistant U.S. Attorney Mark Dispoto said in court Monday.

“That’s the message he wanted to send to the world in advance of this incident” he said.

Routh is currently charged with illegally possessing his gun despite multiple felony convictions, including two charges of possessing stolen goods in 2002 and with possessing a firearm with an obliterated serial number. But Dispoto said in court Monday that prosecutors would pursue more charges before a grand jury accusing him of having tried to “assassinate a major political candidate” — charges that would warrant life in prison if convicted.