The Trump-Ukraine scandal began in September 2019 with the revelation that an intelligence officer had filed a whistleblower complaint to the intelligence community inspector general alleging wrongdoing on the part of Trump.

The whistleblower, who we now know was a member of the CIA and detailed to the National Security Council, claimed that a phone call in July 2019 between Trump and Ukrainian President Volodymyr Zelensky set off alarm bells in the intelligence community. He writes in the complaint: “The White House officials who told me this information were deeply disturbed by what had transpired in the phone call.”

Specifically, he alleges:

In the course of my official duties, I have received information from multiple U.S. Government officials 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. This interference includes, among other things, pressuring a foreign country to investigate one of the President’s main domestic political rivals. The President’s personal lawyer, Mr. Rudolph Giuliani, is a central figure in this effort. Attorney General Barr appears to be involved as well.

The whistleblower also wrote of a possible cover-up by the White House:

In the days following the phone call, I learned from multiple U.S. officials that senior White House officials had intervened to “lock down” all records of the phone call, especially the official word-for-word transcript of the call that was produced — as is customary — by the White House Situation Room. This set of actions underscored to me that White House officials understood the gravity of what had transpired in the call.

The whistleblower had followed the procedure laid out in law for intelligence professionals who believe wrongdoing is taking place. Rather than leaking to the press, intelligence professionals are supposed to file a report with the inspector general. Under the Intelligence Community Whistleblower Protection Act, if the inspector general deems the complaint to be credible and the matter to be of “urgent concern,” he or she is supposed to forward it to the director of national intelligence, who then is required to forward the complaint to Congress within seven days.

But when Director of National Intelligence Joseph Maguire got the complaint, he didn’t forward it to Congress. Instead, he asked the Justice Department’s Office of Legal Counsel what he should do. The office concluded that it was not a matter of urgent concern and that Maguire should therefore sit on the report. The statute does not give the director nor the Office of Legal Counsel discretion over the question of “urgent concern.” The inspector general is given this responsibility and, in this case, that assessment had already been made. Nonetheless, Maguire followed the Office of Legal Counsel’s instructions and did not forward the report.

The existence of the report and the hold-up at the Justice Department came to light in mid-September. By September 19, we learned that the subject of the whistleblower’s report was Trump’s effort to get the government of Ukraine to gin up an investigation into Hunter Biden, the son of Joe Biden, the former vice president and Democratic presidential candidate.

Controversy about this raged for several days, until the White House made an abrupt about-face and allowed both the whistleblower’s report and the official White House record of Trump’s phone call with Zelensky to become public on September 25 and 26.

Trump and his allies waged an on-again, off-again campaign to discredit the whistleblower — arguing both that he is biased against Trump and also that he didn’t have first-hand knowledge of the situation he was writing about. Trump threw in vague calls to unmask him.

....the Whistleblower, and also the person who gave all of the false information to him. This is simply about a phone conversation that could not have been nicer, warmer, or better. No pressure at all (as confirmed by Ukrainian Pres.). It is just another Democrat Hoax! — Donald J. Trump (@realDonaldTrump) October 1, 2019

The memo itself, however, was almost entirely overtaken by subsequent events and corroborated by other sources. The call record showed exactly what the memo said it showed (see below). Testimony by senior officials made it clear that Rudy Giuliani was deeply involved in Ukraine policy despite not holding any government position. And Trump himself in extemporaneous remarks essentially admitted that he wanted Ukraine to investigate Biden. I would think that if they were honest about it, they’d start a major investigation into the Bidens. It’s a very simple answer. They should investigate the Bidens ... and by the way, likewise, China should start an investigation into the Bidens. Because what happened to China is just about as bad as what happened with Ukraine.