After a laborious process, the reporters from Folha were able to unearth what may be the most important evidence of American involvement in the overthrow of the democratically elected, but leftist-populist, government of Jango Goulart. Because it precedes the coup in four months and its recommendations are what actually happened on April 1st, 1964 (a date changed in school books to 31st of March, to not become popularly dubbed Fool's Day or April), it shows that the Brazilian military was probably incited to overthrow the Goulart administration.

In it, the two diplomats list possible outcomes for the institutional crisis happening in Brazil at the time and suggest possible actions to be taken by the American government.

One of them calls attention for being a proposal of action by the White House. It is in item C of the page six, under the title "Removal of Goulart by Constructive Forces", foresees American "persuasion", so that the then president of Brazil leaves the government, and the Speaker of the Parliament, Ranieri Mazzilli, succeeds him, with "temporary military action for support".

Then, says the document, the U.S. would have to take a "constructive and friendly attitude" in relation to the new government. The document was delivered on 6th of January 1964 to the U.S. National Security officer McGeorge Bundy and to other graduated employees of president Lyndon B. Johnson's White House.

Differently from the other documents relating to the period that were set free by American authorities in 2004, this was not added to the electronic archive. The originals rest in a folder of one of the thousands of boxes of the section of College Park of the National Archives, in the State of Maryland.

The document was cited only by the title in a list prepared by the American Department of State, and still only in a footnote. That intrigued the reporters from Folha, who spent months looking for it, to read its content. After searching in three different remittances of four sets of ten boxes, an employee of the archive tried to dissuade the Brazilian journalists from going further. But in the fifth set of files, containing thousands of notes, memorandum and documents, the original typewritten pages were found and copied by the periodical.

A telegram sent on 28th of March is an even bigger proof of American direct involvement in putting Brazil under a 21-year-long military regime. The telegram, also by ambassador Gordon, asks for "a clandestine delivery of weapons not from America" to support Marshal Castello Branco (three days before he would become the first of five non-elected military presidents). He specifically asked for a "secret submarine" and for a small "naval force" to be sent to international waters near Rio de Janeiro's shore. Just in case the Brazilian tanks would face resistance from the population, which did not happen (it was a one-tank putsch, without resistance).

Called operation "Brother Sam", it includes a series of confidential letters from March 1964 to the U.S. government, asking for the secret sending of ammunition and crying gas, probably to help the police repression that ensued the coup. Also there is recommendation of having available fighter jets and ships with missiles.

The documents asking for military support have a signature of approval by the U.S. Armed Forces.

Folha found the author of the plan, Lincoln Gordon, now 93, living in a Senior Citizen Home close to Washington. He justified his actions saying that Brazil "could turn into a second Cuba".