The New York Times is claiming the whistleblower behind a complaint made about a phone conversation between President Trump and his Ukrainian counterpart is a male CIA officer who at one point had been detailed to the White House.

The report, which the Times says was corroborated by three sources, paints the most detailed portrait of the insider to this point, though he has yet to be named publicly.

The Times also reports that, based on the wording of his complaint, the whistleblower likely has extensive knowledge of Ukrainian politics.

The whistleblower came forward in a nine-page complaint — made public Thursday — to allege a White House cover-up of the July phone call in which Trump requested Ukrainian President Volodymyr Zelensky open an investigation into the son of political rival Joe Biden.

The Times defended its decision to publish information on the whistleblower, arguing that the context of the person’s position and expertise lends credibility to his complaint.