Prosecutors said in a filing that law enforcement was contacted by a person who said Routh had dropped off a box at his home several months before his Sept. 15 arrest that contained ammunition, four phones and several handwritten letters, including one addressed to “The World” that stated Routh’s intent in the incident at Trump International Golf Club in West Palm Beach, Fla.

“This was an assassination attempt on Donald Trump but I failed you,” the letter read.

Prosecutors said that between Aug. 18 and the apparent assassination attempt on Sept. 15, Routh traveled from Greensboro, N.C., to West Palm Beach “on multiple days and times” and cellphone data placed him near the golf course and Trump’s Mar-a-Lago home.

They added that six cellphones and a Google search of how to travel from Palm Beach County to Mexico, were found inside the vehicle Routh was stopped in on Sept. 15.

The vehicle also contained several documents including a list of dates in August, September and October alongside venues where Trump was set to appear as well as a notebook containing phone numbers and discussions on how to join Ukraine fighters battling Russian forces and criticism of the Kremlin and China.

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

Secret Service agents moving ahead of Trump playing golf on Sept. 15 found a man in the bushes along a fence line with his face partially obscured and the barrel of a rifle. Agents said Routh fled when they fired on him but with the help of a witness later stopped his vehicle on Interstate 95.

A rifle was found at the scene where Routh was allegedly camped out and authorities said fingerprints on the weapon match Routh’s.