WASHINGTON (AP) - Key dates related to the Trump impeachment investigation:

JULY 24, 2019

Special counsel Robert Mueller testifies before Congress that President Donald Trump was not cleared of obstructing justice, nor was he completely exonerated in the Russia probe, as Trump has contended. Mueller issues a stark warning about the dangers of Russian interference in American elections.

JULY 25, 2019

Trump has a phone call with Ukrainian President Volodymyr Zelenskiy during which he solicits Zelenskiy’s help in gathering potentially damaging information about his principal Democratic rival, former Vice President Joe Biden.

BETWEEN JULY 25 AND AUG. 12, 2019

An unidentified CIA officer files a complaint with the agency alleging misconduct during the president’s July 25 call, according to a person familiar with the matter.

JULY 26, 2019

U.S. Special Representative for Ukraine Negotiations Kurt Volker visits Kyiv and meets with Zelenskiy and various Ukrainian political officials, according to a whistleblower complaint addressed to Congress and delivered to the intelligence community’s inspector general. U.S. Ambassador to the European Union Gordon Sondland also participates, and the two reportedly provide advice on how to “navigate” the president’s demands.

ON OR ABOUT AUG. 2, 2019

Trump lawyer Rudy Giuliani reportedly travels to Madrid to meet with one of Zelenskiy’s advisers, Andriy Yermak, according to a whistleblower complaint.

AUG. 12, 2019

A whistleblower complaint bearing this date and intended for Congress states: “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.” The complaint is addressed to Sen. Richard Burr, R-N.C., chairman of the Senate Select Committee on Intelligence, and Rep. Adam Schiff, D-Calif., chairman of the House Permanent Select Committee on Intelligence. It does not reach them until more than a month later.

AUG. 14, 2019

The whistleblower’s original complaint to the CIA is brought up by Courtney Simmons Elwood, general counsel for the CIA, during a call involving U.S. national security officials, including John Eisenberg, a White House lawyer, and John Demers, who leads the Justice Department’s national security division, according to a person familiar with the matter. Toward the end of that conversation, Elwood says she has received a complaint from someone who raised concerns about a White House phone call they heard about, the person said.

AUG. 15, 2019

Demers goes to the White House to review materials associated with the Zelenskiy call.

AUG. 26, 2019:

Michael Atkinson, the inspector general for the intelligence community, sends a letter to the acting director of national intelligence informing him that the IG’s office has received a complaint addressed to Congress of “urgent concern” about a call between Trump and Zelenskiy. The inspector general says he believes the conversation could have amounted to a federal campaign finance crime.

SEPT. 3, 2019

The Justice Department’s office of legal counsel sends a memorandum to a lawyer at the Office of the Director of National Intelligence, finding that the “alleged misconduct does not involve any member of the intelligence community” and concludes that the Aug. 12 complaint does not meet the statutory requirement as a matter of “urgent concern” that would require it to be forwarded to Congress.

SEPT. 9, 2019

The inspector general for the intelligence community sends a letter to Schiff and Ranking Member Devin Nunes about the whistleblower’s complaint, saying that withholding it “does not appear to be consistent with past practice” because the acting DNI, Joseph Maguire, is not permitting its release to Congress. Atkinson, the inspector general, said in the letter that he is working with Maguire to try to bring the whistleblower’s concerns to Congress.

SEPT. 11, 2019

The White House informs lawmakers that it is releasing $250 million in military aid to Ukraine. The United States began providing military aid to the government of Ukraine shortly after Russia illegally annexed Ukraine’s Crimean peninsula in 2014. The $250 million in funding had been delayed because “The President has been consulting with his national security leadership team to determine the best use of Ukraine security assistance funds to achieve US national security interests,” Office of Management and Budget staff wrote in an email to House Appropriations Committee staff aides.

SEPT. 19, 2019

Atkinson testifies behind closed doors to members of the House Intelligence Committee about the whistleblower’s complaint. Atkinson does not give details about the substance of the complaint.

Also, the president begins responding to published reports about his phone call, tweeting that he understands many people from various U.S. agencies listen in. “Knowing all of this, is anybody dumb enough to believe that I would say something inappropriate with a foreign leader while on such a potentially “heavily populated” call. I would only do what is right anyway, and only do good for the USA!”

SEPT. 24, 2019

House Speaker Nancy Pelosi announces that the House is moving forward with official impeachment inquiry, saying, “No one is above the law.”

SEPT. 25, 2019

The White House releases a rough transcript of the president’s July 25 call with Zelenskiy, confirming that Trump has pushed Ukraine’s leader to work with Giuliani and Attorney General William Barr to investigate Biden and his son. The Justice Department releases a statement saying prosecutors reviewed the inspector general’s referral about a possible campaign finance violation and determined that no crime was committed.

The whistleblower’s Aug. 12 complaint is also transmitted to Congress.

SEPT. 26, 2019

The House Intelligence Committee releases a redacted version of the whistleblower complaint at the center of Democrats’ impeachment probe. The committee also receives testimony from Maguire, who says the whistleblower “did the right thing” by coming forward to report concerns over the White House’s handling of the call between Trump and Ukraine’s leader.

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