Washington - The whistleblower's identity remains obscured, the details of his work for the CIA cloaked in secrecy. But the document he delivered reveals almost as much about the investigative mission he carried out in stealth as it does about the alleged abuses of power by the president.
From the moment he learned about President Donald Trump's attempts to extract political dirt on former vice president Joe Biden from the newly elected leader of Ukraine on July 25, the CIA officer behind the whistleblower report moved swiftly behind the scenes to assemble material from at least a half-dozen highly placed - and equally dismayed - U.S. officials.
He wove their accounts with other painstakingly gathered material on everything from the intervention of Trump's personal lawyer Rudy Giuliani in the U.S.-Ukraine relationship to alleged efforts by American diplomats sent to Kiev and attorneys in the Office of the White House Counsel to contain or suppress the accruing damage.
On August 12, he delivered his document - a nine-page version of which was made public on Thursday - to the intelligence community's inspector general, triggering an almost immediate clash between the executive branch and Congress.
Six weeks later, the whistleblower has by some measures managed to exceed what former special counsel Robert Mueller III accomplished in two years of investigating Trump: producing a file so concerning and factually sound that it has almost single-handedly set in motion the gears of impeachment.
"In the course of my official duties," the whistleblower writes in the first sentence of his complaint, he says he learned that "the President of the United States is using the power of his office to solicit interference from a foreign country in the 2020 U.S. election."
The file goes on to bolster that contention with specific language that matches the since-released White House summary of Trump's call with the Ukrainian president and points to other potential witnesses and grave allegations.
Perhaps the most explosive is the document's assertion that White House officials used a classified computer system to hide documents that might be politically damaging to the president.
Among them, the document says, was the rough transcript of the call with Ukrainian President Volodymyr Zelensky, in which Trump urged his foreign counterpart to mount investigations that would potentially deliver damaging information about Biden and his family.
The detailed notes of that call released this week show that the whistleblower's depictions - having neither heard the conversation nor seen the transcripts - were eerily accurate. The contents of the call alone were widely regarded as politically damaging to the president.
The whistleblower report raises troubling new allegations about the call, saying that White House officials quickly moved it from a widely shared internal computer network to one reserved for "codeword-level" records about CIA covert action programs or other highly classified material.
If true, that could implicate those who directed the relocation of the files and serve as evidence of their motivation: concealing presidential conduct they understood to be problematic and potentially illegal.
A paragraph in the appendix asserts this was not an isolated incident.
"According to multiple White House officials I spoke with," the document says, White House lawyers had on other occasions used the "codeword-level system solely for the purpose of protecting politically sensitive - rather than national security sensitive - information."
Trump, speaking at the United Nations in New York on Thursday, disparaged the author of the report, saying that he was "almost a spy" and potentially guilty of "treason."
Attacking his accusers is one of Trump's standard tactics when thrown on the defensive. He repeatedly accused Mueller and other investigators on the Russia inquiry of being dishonest, beholden to Democrats and engaged in a politically motivated "witch hunt."
Significant differences between the Russia investigation and the whistleblower complaint, however, may make it more difficult for Trump to rely on such tactics. Among them are the accuser's anonymity, the existence of a transcript that many regard as formidable proof of the underlying allegation and the speed with which the complaint has already transformed the political landscape in Washington.
"He'll be remembered as a truth-seeker," said Douglas Brinkley, a presidential historian at Rice University. If and when his identity is revealed, "it'll be one of those names in the history books and around forever, like Daniel Ellsberg," who was responsible for the release of the Pentagon Papers.
Trump has all but called for the whistleblower and those who assisted him to be unmasked, despite federal laws designed to protect identities and prevent reprisals in such cases.
"I want to know who's the person who gave the whistleblower . . . the information," the president said Thursday.
Other officials have said they are intentionally not seeking information about his identity. Joseph Maguire, the acting director of national intelligence, testified Thursday that he does not know who wrote the document. A Justice Department file related to the case noted that the inspector general found "some indicia of an arguable political bias on the part of the complainant," but Maguire said he did not question the whistleblower's motivations.
"I think the whistleblower did the right thing," he said. "I think he followed the law every step of the way."
Although his name has not been disclosed, aspects of his background have emerged. He works for the CIA, an affiliation first reported by the New York Times on Thursday, according to current and former officials familiar with his identity and position in the intelligence community.
U.S. officials and an attorney for the whistleblower have asked news organisations to refrain from releasing details about him, citing concerns for his privacy and safety.
In the complaint, the whistleblower describes receiving troubling reports about the Trump administration's approach with Ukraine from "more than half a dozen U.S. officials" over four months.
But the document suggests that it was only after learning about the nature of Trump's call July 25 with Zelensky that the whistleblower went from sharing colleagues' concerns to being convinced that he needed to document and report them.
An approximate transcript released by the White House shows Trump prodding Zelensky to direct his government's investigative bodies to turn their attention to alleged corruption by an energy company for which Hunter Biden, the former vice president's son, had served as a board member.
Trump has alleged that the elder Biden used his influence to shut down a corruption investigation targeting the company. The claim has been repeatedly discredited, and there is no credible public allegation that Hunter Biden was guilty of wrongdoing.
Trump also urged Zelensky to "meet or speak with" Giuliani and Attorney General William Barr to redouble Ukraine's efforts to seek damaging material tied to Biden.
"Multiple White House officials with direct knowledge of the call informed me that, after an initial exchange of pleasantries, the president used the remainder of the call to advance his personal interests," the whistleblower report says.
The document also cites other developments that allegedly troubled White House officials, including the abrupt removal of the U.S. ambassador to Ukraine in May after a campaign by right-wing media entities to discredit her.
Although the report does not describe explicit coordination between the whistleblower and White House officials, it depicts an arrangement in which he came to serve as their conduit. It is not clear whether they knew of his intention to incorporate their information into a report he was drafting for the inspector general.
The report refers to a "discussion ongoing" between those troubled by the call and White House lawyers, indicating administration attorneys were aware of internal concerns about Trump's conduct before the whistleblower complaint surfaced.
The report lays out investigative leads for Congress or other authorities. It notes that there were "approximately a dozen White House officials who listened to the call" and identifies a State Department official - referred to with conspicuous formality as "Mr. T. Ulrich Brechbuhl" - as another participant.
Brechbuhl had only joined the State Department in May as an adviser to Secretary of State Mike Pompeo.
Beyond his sourcing at the White House, the whistleblower has remarkable insight into the activities of U.S. diplomats and Ukrainian officials. The report notes that Kurt Volker, the U.S. special representative for Ukraine, and Gordon Sondland, the U.S. ambassador to the European Union, arrived in Kiev the day after Trump's call and proceeded to advise officials there on how to "navigate" the demands of the American president.
The document also traces Giuliani's extensive intervention in U.S.-Ukraine affairs, including a meeting in Madrid with one of Zelensky's senior advisers. The Madrid trip was described as a "direct follow-up" to the Trump-Zelensky call, for a more fulsome discussion of the "cases" mentioned in the two leaders' discussion.
At its core, the complaint makes the case that Trump was withholding items that Ukraine desperately wanted - including hundreds of millions of dollars in aid and an invitation to the White House - to use as leverage.
The Trump administration had been sending those signals since Zelensky's inauguration on May 20. American officials who travelled to Kiev to attend the ceremony "made clear" to the Ukrainians that Trump would not meet the new leader until he saw how Zelensky "chose to act," according to the document. Any meeting or phone call would hinge on the Ukrainian president's willingness to "play ball" with his American counterpart, the whistleblower wrote.