Ahead of a detention hearing Monday, federal prosecutors revealed that Ryan Wesley Routh, the 58-year-old man accused of attempting to assassinate former President Donald Trump at his golf course in Florida, wrote a letter months earlier declaring his intent to kill the former president.

The note was a focal point for prosecutors urging a judge to detain Routh ahead of trial following the Sept. 15 incident.

The letter — which was addressed to “The World” — states plainly that it was “an assassination attempt on Donald Trump” and continued with an apology, stating he was “so sorry I failed you.”

Court records obtained by HuffPost Monday indicate that witnesses told investigators Routh left a box at the home of a witness containing the ammunition as well as a metal pipe, phones and the letter months ago.

Prosecutors allege that a Secret Service agent said he spotted the long black barrel of a rifle sticking out from the trees just ahead of where the former president was playing golf earlier this month. Routh was seen fleeing the scene by a witness and then driving away.