Michael Atkinson, who had served as the intelligence community inspector general since May 2018, was the first to alert Congress last year of an “urgent” whistleblower complaint. The complaint was about Trump’s attempt to solicit foreign aid in the 2020 election by withholding military aid from Ukraine in exchange for dirt on Joe Biden. The complaint was submitted by a CIA official assigned to the White House under the provisions of the Intelligence Community Whistleblower Protection Act, making it a lawful disclosure. Atkinson, upon further investigation, found the claim to be credible and urgent, submitting it to the Direct of National Intelligence. In this way, Atkinson served merely to determine if any further investigation was needed, acting as a messenger.

Trump was ultimately impeached for the ensuing findings. He referred to the impeachment as a lynching. He also lied about the Ukranian President having exonerated him. After impeachment, Trump was acquitted by the Senate, which requires 67 votes to convict. The only Senator to break party lines was Republican Mitt Romney. Trump made a teasing remark upon discovering he was in isolation for COVID-19.

Trump directly stated that his firing of Atkinson’s firing amid the COVID-19 pandemic was reprisal for the “fake report.”

The New York Times – Trump Pressed Ukraine’s Leader on Inquiry Into Biden’s Son
Reuters – Trump fires intelligence official involved in his impeachment probe
The Hill – Trump fires intelligence community watchdog who flagged Ukraine whistleblower complaint