JUST IN: Would-Be Trump Shooter's Stunning Letter Is Revealed

Hours before would-be Trump shooter Ryan Wesley Routh makes his first appearance in court, prosecutors unveiled his alleged letter explaining his reasons for aiming a rifle at the former president last weekend.

In new filings, federal authorities describe a plain white letter that confirms Routh's movements along the perimeter of President Trump's golf course were part of a plan he hatched to shoot and kill the Republican on the fifth hole of his golf game that day. News of the letter came from an individual who claimed that Routh dropped off a box at his home months earlier which they said "contained ammunition, a metal pipe, miscellaneous building materials, tools, four phones, and various letters," prosecutors wrote. Addressed to "The World," the letter said, "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."

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As for what prompted the unhinged 58-year-old to try and enact his plan, the letter adds certainly to the theory that Routh was dissatisfied with President Trump's international diplomacy. He "ended relations with Iran like a child and now the Middle East has unraveled," the letter states, according to CNN. Within days, other outlets had uncovered that Routh previously traveled to Ukraine in a bid to support the country's war with Russia. The New York Times confirmed last week that it had interviewed the Hawaii resident about his plan to recruit an international band of fighters to take up the country's cause.

Monday's detention hearing will see Routh charged with two firearms offenses, including the elimination of a serial number on the AK-47-style rifle he is said to have dropped outside the Trump International Golf Course in West Palm Beach. Secret Service agents opened fire on Routh after spotting the rifle's barrel jutting out along the fence line, prompting Routh to allegedly drop his firearm and a backpack containing a GoPro camera and other reconnaissance items. He was later pulled over in a fleeing vehicle. Authorities believe Routh was unable to fire any rounds at Trump.

Cell phone data to be presented in court also purports to show Routh having lied in wait up to 12 hours before President Trump crossed into his line of sight. Prosecutors also claim he stalked Trump's Mar-a-Lago property several times in the months leading up to his assassination attempt, the second against Trump in as many months. Evidence presented on Monday will also show that Routh appears to have had a handwritten list of dates and venues where President Trump would be speaking in the run-up to the November 5th election.