The Justice Department released a chilling letter written by would-be Trump assassin Ryan Wesley Routh on Monday.

The DOJ obtained the letter from a witness who says they received it inside a box delivered to them by Routh several months prior to the assassination attempt. Authorities say the witness opened the box only after hearing Routh was suspected in the attack.

The box contained several handwritten letters as well as ammunition, among other things. One of the letters, addressed “Dear World,” discussed the assassination attempt.

“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,” Routh wrote.

WATCH ON FOX NATION: THE ATTEMPTED ASSASSINATIONS OF DONALD TRUMP

“Everyone across the globe from the youngest to the oldest know that Trump is unfit to be anything, much less a U.S. president,” the letter continues. “U.S. presidents must at bare minimum embody the moral fabric that is America, and be kind, caring and selfless and always stand for humanity. Trump fails to understand any of [that].”

Investigators say they also found a book Routh had authored in 2023, titled “Ukraine’s Unwinnable War: The Fatal Flaw of Democracy, World Abandonment and the Global Citizen-Taiwan, Afghanistan, North Korea, WWIII and the End of Humanity.”

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The rifle Ryan Wesley Routh had during his alleged assassination attempt against former President Trump.

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The book also discusses a Trump assassination, this time encouraging Iran to carry it out.

“In the book, ROUTH stated that he ‘must take part of the blame for the [person] that we elected for our next president that ended up being brainless, but I am man enough to say that I misjudged and made a terrible mistake and Iran, I apologize. You are free to assassinate Trump as well as me for that error in judgment and the dismantling of the deal,” DOJ documents say.

READ THE FULL JUSTICE DEPARTMENT MEMO BELOW. ON MOBILE? CLICK HERE

Routh has been charged federally with possessing a gun with a scratched-out number and with possessing a gun illegally as a felon, though more serious charges are likely pending.

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He is due back in court later this month, and charges could include aggravated assault for allegedly pointing the rifle at a Secret Service agent and making threats against a former president, State Attorney Dave Aronberg previously told Fox News Digital.

Florida Gov. Ron DeSantis said in a press conference Tuesday that Florida will pursue more charges against Routh and that his offense should merit life in prison.  

Fox News’ Mollie Markowitz contributed to this report