• Prosecutors say the man accused in the apparent assassination attempt of Donald Trump previously wrote a letter.
• “This was an assassination attempt on Donald Trump but I am so sorry I failed you,” the letter read.
• The letter was found in a box dropped off months prior to the September 15 incident, feds say.

The suspect accused in the apparent assassination attempt of Donald Trump previously wrote a letter confirming his intent to kill the former president, federal prosecutors said in a new court filing on Monday.

Three days after the September 15 incident that unfolded as Trump was golfing at his West Palm Beach, Florida, club, law enforcement was contacted by a civilian who claimed that suspect Ryan Wesley Routh dropped off a box at his home months prior.

That box contained contained a handwritten note that began, “Dear World,” according to the court filing.

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

According to the prosecutors, the unidentified person who was in possession of the box said that they opened the box only after learning of the apparent assassination attempt on Trump at Trump International Golf Club.

Routh has been charged with possession of a firearm by a convicted felon and possession of a firearm with an obliterated serial number.

Attorneys for him did not immediately respond to a request for comment by Business Insider.