WASHINGTON — The man accused in the apparent assassination attempt of Donald Trump wrote a note months earlier saying that he intended to kill the former president, the Justice Department disclosed Monday in arguing that he should remain locked up as the case moves forward.

The note, addressed “Dear World,” was placed in a box that was dropped at the home of an unidentified person who contacted law enforcement officials after last Sunday’s arrest of Ryan Wesley Routh.

The box, which also contained ammunition, a metal pipe and other items, was not opened by the person until after Routh was taken into custody. The person who received the box and contacted law enforcement was not identified in the Justice Department’s detention memo Monday.

“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.

An attorney for Routh didn’t immediately respond to an email seeking comment Monday morning.